The author(s) shown below used Federal funds provided by the U.S. 

Department of Justice and prepared the following final report:

Document Title: The Acquisition of Sebaceous Fingerprint 

Topology Using Columnar Thin Films (CTF) on 

Forensically Relevant Substrates

Author(s): Robert Shaler, Akhlesh Lakhtakia

Document No.: 244195

Date Received: November 2013

Award Number: 2010-DN-BX-K232

This report has not been published by the U.S. Department of Justice. 

To provide better customer service, NCJRS has made this Federallyfunded grant report available electronically. 

Opinions or points of view expressed are those 

of the author(s) and do not necessarily reflect 

the official position or policies of the U.S. 

Department of Justice.
1 

Final Technical Report 

Report Title: The Acquisition of Sebaceous Fingerprint Topology Using Columnar Thin 

Films (CTF) on Forensically Relevant Substrates

Award Number: 2010-DN-BX-K232 

Authors: Robert C. Shaler and Akhlesh Lakhtakia 

Date: June 22, 2013 

Abstract 

The purpose of this basic-science research project was to expand on successfully completed 

proof-of-concept experiments by, first, determining the scientific basis of and the application of 

columnar thin films (CTFs) to capture friction ridge detail found in latent fingerprints on

nonporous forensically relevant textured substrates and then to compare CTF development of 

fingerprints with commonly employed fingerprint development techniques used for that purpose. 

Latent, sebaceous fingerprints were deposited on forensically relevant substrates, and then CTFs 

were deposited on these latent fingerprints using the conformal-evaporated-film-by-rotation (CEFR) 

technique. The specific objective of this basic research was to investigate the fundamental scientific 

and physical characteristics required to use CTFs to capture and visualize latent, sebaceous 

fingerprints by identifying the necessary CTF materials and deposition conditions required to 

develop fingerprints on selected forensically relevant substrates. Secondarily, the research 

design included a comparison of CTF-developed prints with traditionally developed fingerprints 

on the same substrates, with minimum variability of factors that could be controlled. 

In order to make comparisons between CTF-developed and traditionally developed prints, 

we needed an objective method for assessing the quality of developed prints. Although there 

are references available in the literature for determining quality (1), none seemed suitable 

for our purposes because they often employ a subjective evaluation of some aspect of the 

developed fingerprint. In order to completely evaluate developed fingerprints objectively, 

we devised a system requiring the successive use of three separate, commercially available 

computer programs that collectively transform a photograph of a fingerprint into a multicolorcoded quality map, change the colors into a red-green-blue (RGB) spectrum, count the number of 

those pixels whose color corresponds to regions of definitive identifiable minutiae, and calculate 

the percentage of the fingerprint area which has definitive identifiable minutiae. The initial 

manipulations in the system are implemented on the FBI’s universal latent workstation 

(ULW). The devised system gave us the ability to completely evaluate fingerprints 

objectively. The system is easy to use and was effective for our purposes. 

The research was divided into two phases: I and II. In Phase I, we determined the scientific 

parameters related to CTF development of fingerprint friction ridge detail on forensically 

relevant substrates. This work entailed optimizing the deposition pressure, average vapor flux 

angle, deposition rate, substrate rotation rate, and CTF thickness on glass slides. Cross sections 

of various thicknesses were taken via scanning electron microscope (SEM) to show that CTF 

morphology does not vary greatly with thickness. We found a cross section of a coated ridge that 

clearly demonstrated the conformal nature of CTF coatings on latent fingerprints. Additionally, 

cross sectional SEM images of several different CTFs taken at various viewing angles were used 

to calibrate a quartz crystal monitor (QCM). Depositions of chalcogenide-glass CTFs were also 

made with the modified-CEFR method for comparison. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
2 

In Phase II, we developed latent, sebaceous fingerprints on various forensically relevant 

nonporous substrates that are difficult or not ideally suited to traditional fingerprint development 

techniques. For each substrate, we developed fingerprints using (i) CTF capture of friction ridge 

detail and (ii) a traditional technique typically employed for that substrate and which gave the 

best results in our laboratory. For some substrates, CTF development was superior. For other 

substrates, the traditional technique was superior. For still other substrates, the two techniques 

showed equal capability of developing fingerprints. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
3 

Table of Contents 

Executive Summary ................................................................................. 5 

Purpose ................................................................................................. 5 

Research design ........................................................................................ 5 

Findings and conclusions ............................................................................ 5 

Data analysis ........................................................................................... 7 

Implications for policy and practice ................................................................ 7 

Main Body .............................................................................................. 9 

I. Introduction .......................................................................................... 9 

I.1. Statement of the problem ......................................................................... 9 

I.2. Literature review.................................................................................... 9 

I.2.1. Nonporous substrates: Metals, handles of weapons 

 (plastics & wood), adhesive tapes .......................................................... 10 

I.2.2. Porous substrates................................................................................. 10

I.2.3. Environmental stress and ageing............................................................... 10

I.2.4. Partial bloody prints ............................................................................ 11

I.2.5. CTF technology ................................................................................ 11

I.2.6. Pitfalls ............................................................................................ 13 

I.3. Statement of hypothesis or rationale for the research ......................................... 13 

II. Methods .............................................................................................. 14 

II.1. General overview and research design ........................................................ 14 

II.2. Initial comprehensive study .................................................................... 14 

II.2.1. Forensically relevant substrates ............................................................. 14 

II.2.2. Fingerprint collection procedure ............................................................. 14 

II.2.3. Evaporant materials ............................................................................ 15 

II.2.4. Optimization of CTF development .......................................................... 15 

II.2.5. Selected traditional development techniques............................................... 15 

II.2.6. Imaging of fingerprints ........................................................................ 16 

II.2.7. Subjective grading of fingerprints ........................................................... 16 

II.3. Depleted fingerprint series ...................................................................... 16 

II.4. Partial bloody fingerprints....................................................................... 17 

II.5. Discharged cartridge casings..................................................................... 17 

II.6. Fluorescent evaporant materials................................................................ 18 

II.7. Preliminary comparison of CTF technique with VMD .................................... 18 

II.8. Objective fingerprint grading system .......................................................... 18 

III. Results .............................................................................................. 21 

III.1. Statement of results ............................................................................. 21 

III.1.1. Initial comprehensive study ................................................................ 21 

III.1.1.1. Phase I: Optimization of CTF development ............................................ 21 

III.1.1.2. Phase II: Comparison with selected traditional development techniques .......... 22 

III.1.2. Depleted fingerprint series .................................................................. 23 

III.1.3. Partial bloody fingerprints..................................................................... 24 

III.1.4. Discharged cartridge casings................................................................. 24 

III.1.5. Fluorescent evaporant materials................... ......................................... 24 

III.1.6. Objective fingerprint grading system ...................................................... 25 

III.1.7. Preliminary comparison of CTF technique with VMD ................................... 25 

III.2. Tables.... ......................................................................................... 26 

III.3. Figures ............................................................................................ 37 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
4 

IV. Conclusions ........................................................................................ 49 

IV.1. Discussion of findings .......................................................................... 49 

IV.2. Implication for policy and practice............................................................. 50 

IV.3. Implication for future research ................................................................. 50 

V. References ........................................................................................... 52 

VI. Dissemination of Research Findings ............................................................ 54 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
5 

Executive Summary 

Purpose

The purpose of this basic-science research project was to expand on successfully completed 

proof-of-concept experiments by: first, determining the scientific basis of and the deposition of 

columnar thin films (CTFs) to capture friction ridge detail found on forensically relevant 

textured substrates, and, second, to compare CTF development of fingerprints with the results of 

commonly employed fingerprint development techniques used. The technique used to capture 

friction ridge detail is the conformal-evaporated-film-by-rotation (CEFR) technique, which is a 

variant of the oblique angle vapor deposition technique that has been used for about 150 years 

to deposit optical thin films. Used to fabricate high-fidelity replicas of biological templates 

such as the eyes of flies and the wings of butterflies (3,4), the CEFR technique is particularly 

suited to fingerprint development because it can deposit thin films at micro- and nano-scales 

over planar and curved substrates. Importantly, this technique is based on thermal evaporation 

combined with simultaneous substrate tilting (for obliquely directed vapor flux) and rapid rotation, 

which causes the columns of nanoscale diameters to grow upright (5,6), making this technique 

highly suitable for the solid-state acquisition of fingerprint topology. The CEFR technique 

was used for all of the CTF fingerprint development in this research project. 

Research design

This research was conducted in two phases: I and II. The first phase of the research, Phase I, 

employed the CEFR technique to determine the scientific basis of the CTF capture of latent friction 

ridge detail. For the initial studies, we deposited chalcogenide glass on sebaceous fingerprints placed 

on glass microscope slides and then varied the critical parameters of the CEFR technique: 

deposition pressure, average vapor flux angle, deposition rate, substrate rotation rate, and film 

thickness. We also used several different evaporant materials. 

Research in Phase II involved creating a series of split, sebaceous fingerprints on various nonporous 

forensically relevant substrates. These fingerprints were developed using various evaporant

materials with the CTF development technique and by traditional fingerprint development 

techniques typically used for that substrate. The specific CTF evaporant material was chosen by 

experimentally determining the best for that substrate. The traditional development technique was 

chosen by experimentally identifying the best of those that were tested. After developing the split 

fingerprints, each split pair was photographed and then analyzed for quality using a quality grading 

system. Initially, a subjective grading system was used, but it was later replaced by an objective 

grading system devised by us. In order to limit variability, the fingerprints of only one donor were 

used in all comparative studies.

Findings and conclusions

The results of the Phase I research are shown in Table 2 for the critical CTF deposition parameters 

for developing sebaceous fingerprints: a base pressure of 10–4 Torr is necessary to capture friction 

ridge detail, significantly less than what was initially predicted (2), an average vapor flux angle 

of 20o, a CTF deposition rate of 1 nm s–1, and a substrate rotation rate of 180 rpm. The optimum 

CTF thickness did depend on the evaporant material. For instance, 50-nm-thick CTFs of gold 

provided optimal contrast on some substrates, whereas the optimal thickness of a CTF of 

chalcogenide glass on other substrates turned out to be 20 times higher. For all other 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
6 

combinations of the evaporant material and substrate tested, the optimal CTF thickness was 

found to lie between 50 and 1000 nm, both inclusive. 

The results of the optimization study are shown in Figs. 3A-E. The results clearly demonstrate the 

development of friction ridge detail to the pore level (Figs. 3B and C). Furthermore, the CTF forms 

on the ridges of the fingerprints (Fig. 3E). This is in contrast with another low-pressure deposition 

technique, Vacuum Metal Deposition (VMD), in which gold is first deposited, the gold typically 

penetrating the fingerprint ridge, followed by a second metal, typically zinc. In VMD, neither metal 

is deposited on the fingerprint ridges. Although a head-to-head comparison between CTF 

development and VMD development was not envisaged for this research project, a preliminary 

comparative study was undertaken towards the end of the project period.

Phase II of the research required the deposition of split sebaceous fingerprints on forensically 

relevant substrates. The following procedures were followed for collecting sebaceous secretions. 

The fingertip was cleansed with ethanol, allowed to dry, and then swiped across the forehead, 

nose, and chin of the donor 20 times. Two fingerprints were placed on a glass slide to remove 

excess sebaceous secretions, and then two fingerprints were placed onto the substrate of interest 

for analysis. This procedure was repeated until the desired number of samples was reached. We 

used one fingerprint donor, unless otherwise noted, in order to minimize variability and 

maximize consistency among experiments. For each experiment, four duplicate fingerprints 

were collected. Fingerprints were aged 24 h prior to development. In subsequent experiments 

where sensitivity of the CTF technique was studied, depletion experiments were necessary. We 

found interference from eccrine secretions, and that forced us to redesign the fingerprint 

collection method. The depletion study was taken to the 300th fingerprint – but, as the sebaceous 

secretions were depleting as each fingerprint was placed on a substrate, eccrine secretions caused 

the fingerprints not to be depleted. We determined that thin plastic wrapped around the finger 

allowed us to obtain fingerprints without eccrine secretion interference. For those sensitivity 

studies, sebaceous secretions were collected as described except that a thin plastic wrap was 

wrapped around the finger, allowing us to collect every 2nd fingerprint until the 12th fingerprint. 

Split, sebaceous fingerprints were deposited on the nonporous substrates shown in Table 1. The 

general category of substrates included: brass (Alloy 260), stainless steel (420 grade), adhesive 

tapes – smooth and sticky sides – (Scotch Duct, Gloss Finish Scotch Multitask, Scotch Masking 

and Gorilla), hard plastics (ABS, nylon), soft plastics (black garbage bags, white grocery bags, 

clear sandwich bags), stained and sealed woods (cherry, walnut). Other forensically relevant 

substrates were also chosen because of their problematic development using traditional 

fingerprint development techniques. These included partial bloody fingerprints on stainless steel 

and other substrates. We also collected fingerprints on 9 mm Luger brass cartridge casings 

discharged from a Ruger P95 pistol 

Each split fingerprint deposited on a nonporous substrate was developed using the optimized 

CTF deposition procedure. Various evaporant materials were used in order to determine the 

evaporant material most appropriate for a particular substrate. This was followed by 

development using a traditional technique typically employed for that substrate; see Table 1. 

This information is presented in Table 3. For example, for latent fingerprints on brass, 

chalcogenide glass (1000 nm thick CTF) was the best CTF evaporant material, whereas black 

powder and cyanoacrylate fuming gave the best results of the all the traditional techniques 

selected. For latent fingerprints on stainless steel, chalcogenide glass and nickel were the best 

evaporant materials, whereas cyanoacrylate fuming and cyanoblue were the best traditional 

techniques. For latent fingerprints on stained and sealed walnut and cherry, ABS (black and 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
7 

white), and nylon, the fluorescent material Alq3 afforded the best CTF development. Dusting 

with white magnetic powder and dusting with black magnetic powder were the best traditional 

techniques for walnut and cherry wood, respectively. Dusting with red fluorescent powder gave 

the best results among the selected traditional technique for developing fingerprints on black 

ABS, white nylon, and black nylon, while dusting with black magnetic powder performed the 

best on white ABS. Soft plastic (black garbage bag) responded best to nickel as the evaporant 

material for CTF development and to dusting with red fluorescent powder. 

Superglue fuming (heat and humidity variation) is a traditional development technique we used 

to develop fingerprints on several of the substrates studied (Table 1). In fact, it was the 

traditional technique of choice for stainless steel (Table 3). In Phase II, we found that a 

combination of cyanoacrylate (superglue) fuming and CTF deposition gave superior results for 

discharged cartridge casings. The reason this hybrid technique works so well is that the 

cyanoacrylate polymer that layers on top of the friction ridge detail after fuming enhances the 

topology of the fingerprint. Since the CTF technique responds well to topological differences 

between the friction ridge detail and the underlying substrate, the enhanced friction ridge 

structure resulting from cyanoacrylate fuming makes the hybrid technique (cyanoacrylate fuming 

followed by CTF development) a potentially valuable fingerprint development technique that 

warrants further study for discharged cartridge casings as well as for other substrates. 

Data analysis 

After each development of split pairs of fingerprints using the CTF technique and the best 

traditional technique studied, the results were photographed and the quality of each assessed. 

We found that it was impossible to assess the true quality of the developed prints using published 

procedures (1) because they involve an element of subjectivity. We wanted a system that 

evaluates quality completely objectively. The system we designed uses three sequential computer 

programs that assess the relative (percent) of the developed fingerprint having definitive 

minutiae (Section II.8). Using this objective grading system, we were able to objectively assess 

the quality of each developed fingerprint and identify which development, CTF or traditional, 

gives the better result. 

Implications for policy and practice 

This research demonstrated that CTF development of fingerprints on nonporous forensically 

relevant substrates that are not ideal for traditional fingerprint techniques gives superior or equal 

results for all of the substrates studied except for masking tape, stainless steel, white ABS, and 

black nylon. Although the CTF development of sebaceous fingerprints is applicable for a wide 

range of substrate types, it appears to be particularly suitable for partial bloody fingerprints, for 

which traditional techniques are inefficacious. Partial bloody fingerprints are problematic with 

respect to the two different aspects of the print that must be developed: the latent (sebaceous) and 

patent (bloody) parts. This research showed that just one CTF deposition was able to develop 

both parts of the fingerprint simultaneously. The CTF technique also holds promise for 

developing fingerprints on discharged cartridge casings using Alq3, a fluorescent material, as the 

evaporant material. 

Other low-pressure techniques are employed for fingerprint development: vacuum superglue 

fuming and VMD. The latter is similar in concept to CTF techniques but substantially different. 

VMD was not one of the traditional development techniques studied as part of this research. A 

comprehensive comparison of the two techniques should be undertaken in future research. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
8 

This research employed ideal, laboratory prepared, sebaceous fingerprints as a first approach. 

Also, fingerprints from a single donor were almost exclusively used in order to best ascertain 

how well the CTF technique compares with traditional development techniques. This, however, 

is not reality because latent fingerprints at crimes scenes have different ratios of eccrine and 

sebaceous secretions (we specifically chose to study sebaceous-only fingerprints). Additionally, 

these fingerprints can be aged longer than the 24-h period we used for our research and are also 

exposed to varying environmental insults (heat, humidity, pollution, etc.). 

Another important finding of this research was that the base pressure of the low-pressure 

chamber used in our proof-of-concept studies (2) was significantly lower than the Phase I 

optimization studies of this project demonstrated was necessary for sebaceous fingerprint 

development. This is important because it means that the low-pressure system required for CTF 

development is not as costly as originally believed. It also paves the way for a field-deployable 

CTF development system. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
9 

Main Body 

I. Introduction 

I.1. Statement of the problem 

While most on-scene and in-laboratory fingerprint development applications employ either 

physical or chemical techniques, none have explicitly explored the texture of the fingerprint 

topology as a basis for development. As fingerprints age or are exposed to environmental stress, 

the chemical and some of the physical characteristics becomes progressively more difficult to 

develop. For instance, drying of the friction ridge detail, in essence the fingerprint residue, 

hinders development. While it is as yet completely unknown for all possible latent fingerprint 

environments, it is expected that – even though the chemical and physical characteristics of 

fingerprint residue may become progressively more difficult for development – sufficient texture 

or topology of the fingerprint may remain that is amenable to textural analysis. 

We must employ a technology that can develop latent fingerprints based on the topological 

characteristics of the fingerprint residue in those circumstances where commonly employed 

techniques might either not work or be ideal. Since a latent fingerprint is deposited as a residue, 

it has texture – ridges, pores and grooves – different from the texture of the substrate upon 

which it is deposited. This is especially true for nonporous substrates. The premise of this 

research project was that latent fingerprints are amenable to Columnar Thin Film (CTF)

acquisition technology. 

The purpose of this project was to expand on successfully completed proof-of-concept 

experiments (2) by: first, determining the scientific basis of and the application of CTFs to capture 

– entomb – the friction ridge detail found on forensically relevant textured substrates and, 

second, to compare CTF development of fingerprints with commonly employed fingerprint 

development techniques. Our proof-of-concept experiments had shown us that CTFs can copy 

the topography of fingerprint residue on selected non-porous substrates (2). 

Although the deposition of CTFs is a well-understood technology (7,8), it has never been 

applied systematically to fingerprint development. In light of the recommendations of the 

National Research Council concerning forensic testing (9), determination of the underlying 

scientific basis of new technology and its limitations, such as CTF fingerprint development, is 

critical. The objectives and goals of this research project were to investigate the fundamental 

scientific and physical characteristics required for CTF capture of latent fingerprint topology by 

identifying the necessary CTF evaporant materials and deposition conditions required to 

develop fingerprints on selected nonporous forensically relevant substrates and then to compare 

CTF developed fingerprints with traditionally developed fingerprints on the same substrates. In 

order to meet these goals, we conducted the research in two overlapping phases covering two 

years.

I.2. Review of literature

Fingerprint uniqueness continually attracts researchers to search to improve locating, visualizing 

and lifting fingerprints at scenes of crimes and visualizing and enhancing them in the 

laboratory. Each fingerprint found at a scene is endowed with a complex and unique blend of 

chemical and physical characteristics, the constituents being a varying composite of secretions 

of the major secretory glands (10). The specific composition of fingerprint residue varies 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
10

depending on the relative contributions of each gland and the specific chemistry of each person 

(10). Fingerprint residue is typically an emulsion: a mixture of water, eccrine secretions (salts, 

proteins, small organic molecules, etc.), sebaceous secretions (mono, di and triglycerides; sterols; 

wax esters; fatty acids, etc.), and other contaminants (blood, cosmetics, etc.). 

Many substrates, on which evidence is found, can be too large to fit into a low-pressure

chamber required for CTF deposition. Still, many forensically relevant substrates can be 

relatively small and will fit into that chamber. Latent fingerprints, even on those substrates for 

which commonly used development techniques are not ideal, should have topographic detail 

that should be amenable to CTF development and subsequent analysis. The substrates and 

fingerprint types that are the focus of this research project are described next. 

I.2.1. Nonporous substrates: Metals, handles of weapons (plastics & wood), adhesive tapes 

Developing a latent fingerprint at the scene or in the laboratory requires an understanding of the 

substrate on which the fingerprint lies (11-21), and knowledge of the specific physical and 

chemical techniques applicable to develop the fingerprint on that specific substrate (11,12). 

For plastics (16,17), tapes (11,12,16,17), and metals in firearms and discharged cartridge 

casings (11,19-21), no set methods exist. Although there may be a logical explanation with 

respect to why discharged cartridge casings may not have useable latent fingerprints (11), prior 

to this research they had not been subjected to CTF analysis. This means that there are a 

variety of techniques used to develop latent fingerprints on these substrates, but there is not one 

that is universally applicable, individually, to all plastics, all metallic substrates, or all tapes 

(11,12), both smooth and sticky sides (18). For metals, recent work suggests that print-etching 

of the metallic substrate can be useful to visualize latent prints (19-21). The etching process 

creates substrate texture that should be amenable to CTF development and analysis. For plastics, 

one common development method involves superglue fuming. However, even this method does 

not work for all plastics, the success depending on the specific fuming method employed 

(15). A method often seemingly more useful for plastics is VMD (11,16,17). For plastic 

substrates, the fingerprint residue should have a texture and therefore be amenable to CTF 

development. 

I.2.2. Porous substrates 

Standard methods exist for developing latent prints on porous substrates. And while it could be 

expected that the usual porous substrates would not be successful with CTF development, this 

is not known. There are porous substrates categorized as hard, that is, those into which the 

sebaceous secretion do not enter rapidly (13). While hard porous substrates may produce CTFdevelopable fingerprints, porous substrates are not the subject of this research project. 

I.2.3. Environmental stress and ageing

Ageing and environmental insults can affect an investigator’s ability to develop latent prints 

(11). Over time, ageing dries the fingerprint residue, which hardens the emulsion making it 

relatively insensitive to common dusting and superglue fuming techniques (22). 

Environmental insults also affect the fingerprint’s emulsion, which will vary in different 

regions of the country and at different seasons of the year. Like ageing, dry, hot weather dries 

the fingerprint residue making it difficult to be analyzed (22). Similarly, cold weather hardens 

the oils in the fingerprint residue, again making it resistant to traditional development techniques. 

Certainly, it is possible to reverse the drying effects somewhat, but this requires an extra 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
11

treatment at the scene, for on-scene development, or in the laboratory (22). 

With respect to all latent fingerprint development, an unknown parameter concerns the 

integrity of the fingerprint residue, whether the damage occurred because of the environment 

or during deposition of the fingerprint. However, if the fingerprint residue is present and it

has texture, regardless of its chemical or physical integrity, it should be amenable to CTF 

development. Research concerning the ability to effect CTF development on environmentally 

insulted fingerprints was not the focus of this research project, but the issues involved must be 

tackled in subsequent research. 

I.2.4. Partial bloody prints

Partial bloody prints are commonly found on objects at a crime scene. Although developmental 

issues for blood enhancement were not addressed in this research project specifically, they can 

pose potential problems if the print is a partial bloody print, where one part of the fingerprint is 

latent and the other patent. Certainly, the bloody, patent part is easily enhanced using common 

protein stains (23). These might also enhance selected areas of the visually latent part if those 

areas are also bloody, even if the amount of blood present were below the detection limits of the 

human eye. From the perspective of this research project, both the latent and patent parts of the

print should have textural detail amenable to CTF development. 

I.2.5. CTF technology

The premise underlying this basic-science research project is that a physical vapor deposition 

(PVD) method called the conformal-evaporated-film-by-rotation (CEFR) technique is 

applicable to fingerprint development with the potential to develop latent fingerprints on 

substrates for which traditional development techniques are either inadequate or not ideal. For 

this work, the formation of upright columnar thin films (CTF) via the CEFR technique was 

used to capture fingerprint topology, a technique fundamentally different from other lowpressure fingerprint development techniques such as vacuum superglue fuming (15) and VMD 

(16,17). 

The technique closest to CTF is VMD, wherein gold is first evaporated in a low-pressure 

chamber to form a thin layer on the exposed substrate, the gold penetrating the fingerprint 

residue. Next, a layer of zinc or cadmium is deposited in the same manner. This second layer 

lies atop the gold layer but supposedly does not penetrate the fingerprint emulsion, leaving the 

fingerprint ridges transparent while the zinc/cadmium background is dark (17). In contrast, the CTF 

forms a conformal coating on the fingerprint ridge and thus maps the topography of the 

fingerprint.

CTF technology has been known for over a hundred years (7,24). CTFs of solid materials have 

been deposited as coatings (7,8,25) for optical, magnetic, electrical, tribological, and other 

purposes. The CTF coatings are assemblies of parallel, straight columns or nanowires. Typically, 

a CTF grows on a planar substrate mounted on a platform, the tops of the columns together 

constituting a surface that is almost planar. When the substrate has a slight undulation, 

possibly due to a dust particle or a manufacturing defect, that undulation, which is highly 

undesirable for most practical CTF applications in such fields as optics or microelectronics, is 

manifested at the top surface (26). Consequently, if a CTF were to be deposited on a fingerprint, the 

top surface of the CTF would be expected to reproduce the topological details of the fingerprint. 

The result could then be visualized using traditional optical techniques, ideally obviating the 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
12

need for subsequent chemical or other physical development methods. Additionally procedures 

that add texture to the existing latent fingerprint residue – superglue fuming, etc. – would be 

expected to enhance CTF formation. 

The concept behind the proposed solid-state acquisition of fingerprint topology can be explained by 

comparing it to a child’s toy called the Pin Point Impression (27) shown in Fig. 1. This toy is a 

dense collection of parallel and identical cylindrical pins. When the pins are made to stand erect 

over a flat surface, the pin heads form collectively a surface that is also flat (Fig. 1, left panel). 

When the pins stand over an undulating surface, the pin heads also form an undulating surface

(Fig.1, right panel), the undulations of the top surface mimicking the undulations of the bottom 

surface. The smaller the cross-sectional radius of the pins and the larger the number density of 

pins, the more faithful will be the replication of the topological features of the bottom substrate

by the top surface created by the pin heads. If the pins of the toy could be glued together, they 

would record the topological features of the undulating substrate.

The Pin Point Impression toy is analogous to the morphology of CTFs whose growth occurs by 

thermal evaporation. In early experiments (2), at a pressure of around 1 μTorr, material 

(chalcogenide glass) in a source boat was electrically heated to evaporate upward toward a 

fingerprint deposited on various substrates; see Fig. 2. The fingerprints face the source boat 

allowing the evaporating material to settle thus forming a dense CTF. Typically, isolated 

nucleation clusters about 1-3 nm in diameter initially form on the substrate, usually without 

reacting chemically with the fingerprint residue. These clusters evolve into expanding and 

competing columns as the film thickness increases. This has been reviewed elsewhere (8). Such 

growth conditions describe most optical thin-film coatings used commercially. 

If the circumscribing cross-sectional radius of a CTF column is denoted by r, the topographic 

features on the substrate of linear cross-sectional dimensions of the order of or larger than r are 

reproduced on the top surface of a CTF comprising nearly perpendicular columns. With r on 

the order of 30 to 300 nm, CTFs made from suitable inorganic materials can replicate 

topographic features on a submicron scale.

Thermal evaporation is the simplest of the PVD techniques used for growing CTFs. Other 

PVD techniques include electron-beam evaporation, sputtering, and laser ablation (7,8,25). 

However, thermal evaporation is the gentlest of the PVD techniques in that the substrate is not 

adversely impacted by the impinging atoms and molecules traveling with high momentums, a 

significant criterion for the high-fidelity replication of a fingerprint. Additionally, the high 

directionality of the evaporant flux facilitates columnar formation and growth (8). Furthermore, 

a significantly large and in-depth understanding of thermal evaporation exists in the scientific 

community, and so do several variations of this technique to achieve high-density CTFs (25).

Among the most recent variations is the CEFR technique, developed to fabricate high-fidelity 

replicas of biological templates such as the eyes of flies and the wings of butterflies (3,4). These 

templates have characteristic features on the micro- and nano-scales distributed over planar as 

well as curved surfaces. The CEFR technique is based on the combination of thermal evaporation 

with simultaneous substrate tilting (for obliquely directed vapor flux) and rapid rotation. The 

combination of substrate tilting and rapid rotation causes the columns of nanoscale diameters to 

grow upright (5,6), making the CEFR technique highly suitable for the solid-state acquisition of 

fingerprint topology, even for fingerprints exposed to environmental stress. The CEFR 

technique was used for all of the CTF fingerprint development in this research. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
13

I.2.6. Pitfalls

Although the successful outcome of the research carried out can have distinct benefits for the 

latent fingerprint community, there are still obstacles to overcome. An obvious one is the size of 

the low-pressure chamber used for CTF deposition. This research project purposely targeted

smaller items of evidence. Importantly, the research results suggest that a redesign of the lowpressure chamber is highly feasible. Additionally, the chamber(s) employed are currently 

laboratory-based systems, a limitation of current technology, and are not amenable to in-the-field 

work. 

Also, the effects of ageing and environmental stresses on fingerprint residue texture are 

unknown. This is important because the CTF method requires a texture different from the 

substrate on which the fingerprint rests.

I.3. Statement of hypothesis or rationale for the research

The rationale for this research is that the topology of latent fingerprint residue is significantly 

different from that of the underlying nonporous substrates, that latent fingerprint development is 

amenable to CTF technology (2), and that it is superior to traditional methods used to develop 

fingerprints for specific substrates where current techniques are either inadequate or not ideal, 

provided that sufficient textural friction ridge detail is present. 

Additionally, the development of friction ridge detail using CTFs is a single technique, which 

means it is applicable to different nonporous substrates and will obviate the need to perform 

complicated chemical or physical techniques – or combinations of techniques in a cascade – in 

order to obtain satisfactory development for specific substrates. Before comparison of 

developmental techniques could begin, we determined the underlying scientific basis of CTF 

development of latent fingerprints. This is in accordance with the 2009 report of the National 

Research Council (9), often referred to as the NAS report, which clearly stated that the scientific 

basis of forensic testing is critical. 

Phase I of this research responded to the NAS report’s suggestions by identifying the underlying 

scientific requirements for the CTF development of latent fingerprints on nonporous relevant 

forensic substrates identified in Table 1. Sections II.2.4 and III.1 of this report show successful 

optimization for the critical parameters of CTF fingerprint development. 

Using the optimized CTF deposition parameters identified in Table 2, we investigated several 

evaporant materials for CTF development for each substrate tested in Phase II. The best 

evaporant material employed for the CTF development, the optimal CTF thickness, and the bestperforming traditional technique used for all substrates investigated in our laboratory are 

summarized in Table 3. Traditional techniques were chosen based on results obtained by other 

investigators. The results presented in Table 4 showed that CTF development of latent 

fingerprints is superior to traditional development techniques for some forensically relevant 

substrates, is not superior for other substrates, and is equal to traditional techniques for other 

substrates. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
14

II. Methods 

II.1. General overview and research design

This was a two-year research program with the ultimate goal of ascertaining whether CTF 

acquisition of fingerprint topology is applicable to developing latent fingerprints in forensically 

relevant scenarios where current techniques are either inadequate or not ideal. The research was 

divided into overlapping phases that were actually a continuous, stepped process, where each 

sample (latent fingerprints on a specific substrate) progressed step-wise from Phase I, 

establishing optimum conditions for the deposition of CTFs on different types of substrates, 

to Phase II, a comparison of CTF-developed fingerprints with traditionally developed prints. 

As each substrate emerged from Phase I optimization, it was immediately taken into Phase II. 

We first conducted a comprehensive study involving the optimization of the CTF development for a 

variety of nonporous forensically relevant substrates and using a variety of evaporant materials. 

Based on the understanding obtained, we went on to investigate the CTF development of (i) 

depleted fingerprints, (ii) partial bloody fingerprints, and (iii) fingerprints on discharged cartridge 

casings. Furthermore, we also compared the use of two different fluorescent materials for the 

deposition of CTFs on fingerprints. For all comparative studies, variability was limited by using the 

same finger of the same donor.

II.2. Initial comprehensive study 

II.2.1. Forensically relevant substrates 

The chosen substrates initially included: (i) brass (Alloy 260), (ii) stainless steel (Grade 420), 

(iii) the sticky and smooth sides of various adhesive tapes (Scotch® Duct, Gloss Finish Scotch® 

Multitask, Scotch® Masking, and Gorilla®), (iv) hard plastics (black and white acrylonitrile 

butadiene styrene (ABS), black and white nylon), (v) soft plastics (clear sandwich bags, white 

grocery bags, black garbage bags), (vi) woods (cherry and walnut, stained and sealed with 

polyurethane), (vii) partial bloody fingerprints on 420 grade stainless steel (whole human blood 

droplets from lanced fingertips), and (viii) discharged cartridge casings (9 mm Luger). All 

substrates––except discharged cartridge casings––were cut into 25 mm 25 mm squares for 

deposition of a latent fingerprint per square. 

II.2.2. Fingerprint collection procedure 

All latent fingerprints were collected using a grooming procedure to ensure as much consistency 

as possible – first, throughout the optimization of the deposition parameters for CTF 

development, and then during comparative studies against traditional development techniques. 

The grooming procedure involved used the same finger at all times to limit variability. The 

finger was first cleansed with ethanol and allowed to dry. The fingertip was then swiped across 

the forehead, nose, and chin of the donor 20 times. Two fingerprints were laid down on a glass 

slide to remove excess sebaceous secretions, and then two fingerprints were laid down on the 

substrate of interest for processing. This procedure was then repeated until the desired number 

of samples was reached. The services of one fingerprint donor, unless otherwise noted, were 

utilized to minimize variability and maximize consistency between experiments. For each 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
15

experiment, four duplicate fingerprints were collected. Fingerprints were allowed to age 24 h 

prior to development. 

II.2.3. Evaporant materials 

The evaporant materials utilized were selected because of their compatibility with PVD (8,25). 

Easily evaporated materials are desirable because they allow for high deposition rates to be 

achieved without producing unnecessary heat that could damage both the substrate under 

investigation and the latent fingerprint thereon. The evaporant materials chosen were: (i) 

chalcogenide glass of nominal composition Ge28Sb12Se60, (ii) gold, (iii) nickel, (iv) magnesium 

fluoride, (v) germanium oxide, and (vi) a fluorescent evaporant Tris (8-hydroxyquinolinato) 

aluminum, more commonly known as Alq3. 

Alq3 is an organometallic chelate that is typically used in organic light-emitting diodes, where 

variations of the quinoline structure can affect its luminescent properties [28]. Deposition of Alq3

produces a developed fingerprint that is visible when exposed to short-wave ultraviolet radiation. 

Germanium oxide is a high-refractive-index material often used to make wide-angle lenses, 

magnesium fluoride is low-refractive-index material often used for anti-reflective coatings, gold 

and nickel are commonly used metals, and chalcogenide glass is an infrared transparent material 

often used for shortwave-infrared applications. This diversity of materials was chosen in order 

to best optimize deposition parameters on various substrates for the best contrast possible. 

II.2.4. Optimization of CTF development 

Prior to comparing the results of the CTF development technique with those of the traditional 

development techniques, a systematic series of experiments was carried out in order to determine 

the optimal CTF-deposition conditions necessary to achieve the highest quality of latent 

fingerprint development. The following parameters were varied within the limitations of a 

custom-made CEFR apparatus (2-6) in order to find their optimal values: (i) base pressure in the 

low-pressure chamber prior to deposition, (ii) average angle of the collimated vapor flux 

relative to the plane of the platform to which the substrate is affixed inside the low-pressure 

chamber, (iii) substrate rotation rate, (iv) deposition rate of the CTF, and (v) thickness (as 

measured by a quartz crystal monitor (QCM) within the low-pressure chamber) of the CTF. The 

base pressure was controlled using a turbo pump, the substrate rotation rate by the rotation 

motor, the deposition rate of the CTF through the electric current passed though a tungsten boat 

holding the evaporant material, and the CTF thickness by a QCM located close to the substrate 

inside the low-pressure chamber. The QCM also provides feedback for deposition control. The 

rocking motor was not used and the angle was held fixed during deposition. The evaporant 

material used for the optimization study was chalcogenide glass of nominal composition 

Ge28Sb12Se60, and the underlying substrates were standard glass microscope slides. 

II.2.5. Selected traditional development techniques 

The CTF development technique was compared to traditional development techniques by 

following a split-fingerprint protocol. A fingerprint was deposited onto two 25mm 12.5mm 

pieces of the selected substrate that were laid side by side, so that half of each fingerprint was 

placed on each piece. Each half was subsequently developed with either the CTF development 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
16

technique or a traditional technique relevant to the specific substrate. 

As indicated in Table 1, the traditional development techniques utilized included: (i) dusting with 

regular black powder, regular white powder, magnetic black powder, magnetic white powder, or 

a fluorescent powder (red, green, yellow, orange); and (ii) cyanoacrylate fuming (with cyanoblue 

dye when applicable) in a commercial chamber (Arrowhead Forensics, Lenexa, KS). The third 

traditional technique involved using either a pre-mixed liquid sold as WetwopTM, sticky-side 

powder (SSP), a small-particle reagent (SPR), leucocrystal violet (LCV), or protein dyes, amido 

black, and acid violet 17, as appropriate for the substrate of interest. 

Following separate developments of both halves of each fingerprint, the two halves were 

reconnected and photographed for grading. 

The performance of the CTF development technique was not comprehensively compared with 

that of VMD (15,16). Both techniques are similar in that they are based on evaporating a material 

in a low-pressure chamber, but they are also very different and are expected to produce very 

different outcomes. 

II.2.6. Imaging of fingerprints 

Both latent and developed fingerprints were photographed with a Nikon D3000 10.2 megapixel 

camera with a Nikon 60mm macro lens capable of 1:1 reproduction. The camera was attached to 

a custom stand that allowed photographs to be taken from the same viewing angle and under the 

same lighting conditions. Higher-magnification (10 to 40 ) optical images of the fingerprints 

were acquired on a National stereo microscope partnered with a Moticam 1000 1.3 megapixel 

microscope camera. 

A Hitachi S-3500N backscattered SEM, capable of resolving 4nm at 25kV and with 

magnification ranging from 15 to 100K , was used to make images on which the columnar 

morphology of CTFs deposited on fingerprints could be resolved. 

II.2.7. Subjective grading of fingerprints 

All fingerprints were graded based on visual observation and comparison. Clarity, contrast, and 

visualization of observable detail of level one/two/three were all considered as developed 

fingerprints were compared side by side. 

II.3. Depleted fingerprint series 

Following the initial comprehensive study, the sensitivity of the CTF technique was studied by 

conducting depletion experiments. Interference from eccrine secretions forced us to redesign the 

fingerprint collection method for sensitivity studies. The depletion study was taken to the 300th 

fingerprint, but as the sebaceous secretions were depleting as each fingerprint was left, eccrine 

secretions were forming from the pores on the fingertips causing the fingerprints not to be 

depleted. Sebaceous secretions were collected as described in Section II.2.2, with the difference 

that a thin plastic wrap was wrapped around the finger to eliminate interference from eccrine 

secretions. This allowed us to collect every 2nd fingerprint until the 12th fingerprint. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
17

The substrates used in the studies included: (i) stainless steel (Grade 420), (ii) brass (Alloy 260), 

(iii) anodized aluminum, and (iv) hard plastics (black and white ABS, black and white nylon). A 

split-print protocol was utilized for the substrates. The protocol required each 25mm x 25mm 

square of the substrate to be cut into two equal rectangles, which were then taped together to 

form the 25mm x 25mm square. A latent fingerprint was placed on the re-formed square, so that 

the fingerprint could be split into two halves, each to be developed by a different technique. This 

protocol allowed for the outcomes of two different techniques to be compared. 

The two halves of a split print were labeled A and B. The half labeled A was developed with the 

CTF technique, and the half labeled B with a traditional technique. The depletion study was 

conducted twice for each substrate. The first time the split print labeled A was on the left with 

the split print labeled B on the right. The second time the split print labeled A was on the right 

and the split print labeled B on the left. This strategy compensated for any variability that could 

occur in how a fingerprint donor laid and put pressure on a substrate. 

For the depletion series, the evaporant materials used included: (i) Alq3, (ii) chalcogenide glass 

of nominal composition Ge28Sb12Se60, (iii) gold, and (iv) nickel. 

II.4. Partial bloody fingerprints 

Inspired by the positive initial indication from the initial comprehensive study described in 

Section II.2, we went on to focus on partial bloody fingerprints on different types of nonporous 

forensically relevant substrates: (i) stainless steel (Grade 420), (ii) brass (Alloy 260), (iii) 

anodized aluminum, (iv) hard plastics (black and white ABS, black and white nylon) and (v) soft 

plastics (clear sandwich bag, white grocery bag, black garbage bag). 

Sebaceous secretions were collected with the grooming procedure described in Section II.2.2. A 

split-print protocol described in Section II.3 was employed. Four fingerprint samples were 

collected for each substrate (split into two). Before each fingerprint was deposited, a drop of 

blood was added to the fingertip from a lanced fingertip. The lanced fingertip was not the same 

fingertip used to deposit the fingerprint. 

For partial bloody fingerprints, the evaporant materials used included: (i) Alq3, (ii) chalcogenide 

glass of nominal composition Ge28Sb12Se60, (iii) gold, (iv) nickel and (v) (1,10-phenanthroline) 

tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato]europium(III) (more commonly known as 

Eu(tta)3phen). 

The traditional development techniques used are provided in Table 1. In addition, fluoroscein 

and hemascein were used. 

II.5. Discharged cartridge casings 

Fingerprints placed on 9 mm Luger cartridge casings prior to their subsequent discharge through 

a Ruger P95 pistol were developed by the hybrid cyanoacrylate-CTF technique used also for 

developing latent fingerprints on adhesive tapes. The fingerprint collection procedure is 

described in Section II.2.2. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
18

A special fixture for mounting the discharged bullet casing to the platform in the low-pressure 

chamber had to be devised and fabricated. Furthermore, as the substrate (bullet casing) is not flat 

but possesses a convex cross section at the macroscopic length scale, the rocking motor was used 

to continually change the average vapor flux angle between 10° and 90° with a temporal period 

of ~ 9 s during deposition. Alq3 was evaporated to deposit a 100-nm-thick CTF. 

II.6. Fluorescent evaporant materials 

In addition to Alq3, we also studied the use of another fluorescent evaporant material: 

Eu(tta)3phen. Comparison was made with fingerprints developed with Alq3 CTFs. 

Sebaceous fingerprints were collected as described in Section II.2.2. Four fingerprints were 

collected on each substrate: (i) stainless steel (Grade 420), (ii) brass (Alloy 260), (iii) hard 

plastics (black and white ABS, black and white nylon) and (iv) glass. The split-print protocol 

explained in Section II.3 was adopted. 

II.7. Preliminary comparison of CTF technique and VMD

Although a head-to-head comparison between CTF development and VMD development was not 

envisaged for this research project, a preliminary comparative study was undertaken towards the end 

of the project period. The morphologies of the thin films deposited on fingermarks on glass were 

examined using a scanning electron microscope. Comparison was also made for the development of 

fingerprints on four types of plastics (clear sandwich bags, white grocery bags, smooth side of Gloss 

Finish Scotch® Multitask tape, and black garbage bags) and partial bloody fingerprints on 

stainless steel, using the split-print methodology described in Sec. II.3.

II.8. Objective fingerprint grading system 

 

Fingerprints were initially graded based on visual observation and comparison, where clarity, 

contrast, and visualization of observable detail of levels one/two/three were all considered. All 

developed fingerprints were compared side by side, as discussed in Section II.2.7. Soon, we 

recognized the need to have a completely objective system for grading quality. 

Thus, an objective quantitative grading system was devised that requires the successive use of 

three separate programs that collectively transform a photograph of a fingerprint into a 

multicolor-coded quality map, change the colors into a red-green-blue (RGB) spectrum, count 

the number of those pixels whose color corresponds to regions of definitive identifiable minutiae, 

and calculate the percentage of the fingerprint area that has definitive identifiable minutiae. We 

found this quality grading system useful for evaluating the efficacy the CTF development 

method and for comparing two development methods using the split-fingerprint approach. 

Using the quantitative quality grading system requires the following: (1) photographing a 

fingerprint before and after development; (2) placing a scale in the photographic plane parallel to 

the plane of the fingerprint, and (3) a viewable scale in the resulting photograph in order to 

reduce as much as possible errors in subsequent processing with the three computer programs. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
19

The first program employed is the Universal Latent Workstation (ULW) developed by the 

Federal Bureau of Investigation (FBI) to help fingerprint examiners to characterize fingerprints 

and then upload them to the Automated Fingerprint Identification System (AFIS). Once a 

photograph has been imported into the program as an image, the user is prompted to provide 

information about pixels per inch (ppi) of the image. The program supports only images having 

a resolution of 1000 ppi. The scale visible within the photograph’s frame helps the program 

identify the number of pixels that fit within a distance of 1 inch. The program then converts the 

image to the proper resolution and into grayscale. 

Within this program, there is a subset of features called the Extended Feature Set wherein an 

Image Quality map is applied to the image of the latent fingerprint. The Image Quality map 

contains the colors black, red, yellow, and green – corresponding to the background, debatable 

ridge flow, debatable minutiae, and definitive minutiae, respectively. In this raw quality map, the 

grayscale photograph of the fingerprint is still visible in the background. Next, the grayscale 

levels, brightness, and contrast are adjusted to leave only the four quality map colors visible. 

This is done by dragging the color adjustment bar at the top of the ULW program fully to the 

right. We refer to the quality map altered in this way as darkened. 

The resulting darkened quality map is exported as a .bmp file and uploaded into the second 

program, which is an image editing program called GIMP (28). In this program, the quality map 

colors assigned by the ULW are transformed into RGB color values represented in digital 8-bit 

notation: black is (0, 0, 0), blue (0, 0, 255), yellow (255, 255, 0), and white (255, 255, 255). 

These values correspond to (0, 0, 0), (0, 0, 1), (1, 1, 0), and (1, 1, 1) when using arithmetic 

notation. The resulting image is saved for a pixel-counting algorithm to be used on it. In the 

GIMP color scheme, black corresponds to background, blue to debatable ridge flow, yellow to 

debatable minutiae, and white to definitive minutiae. We decided to rate the image quality based 

on the percentage of the image area that is white, i.e., identified as having definitive minutiae. 

This is done using a Mathematica® (29) program devised specially for this purpose. In this 

program, the image is represented as an N x M matrix where N is the width of the image in 

pixels and M is the height of the image in pixels. Each element of this matrix contains the RGB 

value of the pixel in the image with the same coordinates. This representation is analogous to a 

vector field in which each coordinate in a 2-Dimensional plane has a 3-Dimensional vector 

associated with it. By our selection of the RGB values we simplify this vector field to a scalar 

field by averaging each of the RGB values. Thus, black (0, 0, 0) becomes 0, blue (0, 0, 1) 

becomes 1/3, yellow (1, 1, 0) becomes 2/3, and white (1, 1, 1) becomes 1, giving us an N x M 

matrix where each element is 1 of 4 possible numbers. Since we are only concerned with the 

occurrence of each value, we simplify the matrix into a list of its elements, reducing our task to 

tallying the number of times that each value appears in the list and the calculating the percentage 

of the image each color represents after subtracting the black background pixels. We utilized the 

percentage of the image identified as containing definitive minutiae before and after 

development as a measure of the performance of the development technique as well as for 

comparing different fingerprint development techniques when using the split fingerprint method. 

The program commands in Mathematica® (either version 7 or 8) are outlined as follows: 

(M1) a = Import[“C:\\Insert Image from GIMP Pathname Here”]; 

(M2) b = ColorQuantize[a,5]; 

(M3) n = ImageDimensions[b]; 

(M4) c = ImageData[b]; 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
20

(M5) e = Table[Mean [c[[A]][[B]]], {A, 1, n[[2]]}, {B, 1, n[[1]]}]; 

(M6) f = Flatten[e]; 

(M7) g = MatrixForm[Sort[Tally[f], #1[[1]] < #2[[1]]&]]; 

(M8) p = Tally[f]; 

(M9) ell = Dimensions[p]; 

(M10) m = ell[[1]]; 

(M11) sum = Total[Table[g[[1]][[k]][[2]],{k,1,m}]]; 

(M12) Fraction[MatrixForm[Table[{3*g[[1]][[k]][1]], N[100*g[[1]][[k]][[2]] / 

 ((sum - g[[1]][[1]][[2]])) “%”, 2]}, {k,2,m}]] 

The command M1 imports the desired image into Mathematica® subsequent to its processing 

with GIMP. Once the image has been imported, use of command M2 downgrades the 

photograph to a given number of colors. This number should be selected to be as low as possible 

without eliminating one of the colors assigned in GIMP. This must be done as when the image is 

exported from the ULW it may contain stray pixels that are not one of the four assigned colors. 

Ideally this value would be 4 but in practice it is selected between 5 and 7. The stray pixels 

account for a fraction of a percentage of the total image. 

Next, command M3 is used in order to call up the dimensions of the image modified with 

command M2 so that pixel counters can be iterated in future commands. Command M4 

generates a matrix with the same dimensions as the photograph modified by command M2 in 

which each matrix component is the RGB value of a pixel corresponding to that matrix element. 

Next, command M5 takes the average of the RGB values generated by command M4 

compressing the RGB value into a single number. The colors assigned in GIMP were selected so 

that this average value would come to 0 for black, 1/3 for blue, 2/3 for yellow and 1 for white. 

The simplified matrix from command M5 is then further reduced to a list by command M6. 

Command M7 then tallies the number of times that each value appears in this list, sorts the tally 

results in ascending order according to the value of the average RGB value from command M5

and reports the results in the form of a matrix with the average RGB value in the left column and 

the number of times of its occurrence in the right column. Command M8 utilizes the tally 

command again to give the total number of elements in the list generated by command M6. This 

is done again in order to use this information in future iterations. Command M9 gives the 

dimension of the matrix that has the color and its number count, for use in future iterations. 

Command M10 is then used to give the number of columns that appear after the execution of 

command M8 so that its result can be used by commands M11 and M12 as the upper limit of an 

iterator. Command M11 then gives the total number of all of the pixels counted by summing the 

results of command M7. Finally, command M12 reports the percentage of the image that is 

composed of each color of interest. Colors are identified by their average RGB values multiplied 

by 3 to give each one as a whole number: 1 for blue, 2 for yellow, and 3 for white. The 

percentage reported is calculated from the blue, yellow and white areas of the image; black 

pixels are excluded. This allows us to consider only the print portion of the photograph when 

comparing the photographs of a fingerprint before and after development. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
21

III. Results 

III.1. Statement of results 

III.1.1. Initial comprehensive study 

III.1.1.1. Phase I: Optimization of CTF development

Five parameters were varied for CTF optimization in Phase I research (as discussed in Section 

II.2.4): base pressure, average vapor flux angle , CTF deposition rate, substrate rotation rate, 

and CTF thickness. The values of these parameters specifically used for optimization are 

presented in Table 2, along with the optimal value of each parameter determined by visual 

observation of clarity, contrast, and level one/two/three detail of the developed fingerprints. The 

optimal values of four of the five parameters turned out to be quite similar to those used in the 

proof-of-principle experiments (2), the sole exception being the base pressure prior to the 

beginning of the CTF deposition. 

Whereas the base pressure was 4.0 10–6 Torr or lower in the predecessor studies (2), it was 

determined that just 1.0 10–4 Torr would suffice for fingerprint development. The adequate base 

pressure thus determined is moderately low, which greatly reduces the requirements on CEFR 

apparatus for fingerprint development. This finding means that an on-scene field-forward 

technique could be designed, and the subsequent expense for CTF fingerprint development 

equipment will be less than originally thought, and the time required to pump down to the base 

pressure significantly reduced. 

The efficacy of the CTF development technique is brought out by the five images presented in 

Fig. 3. Photographs of a fingerprint on a glass slide are shown in Figs. 3A and 3B, respectively, 

before and after development using the optimal conditions identified in Table 2. The latent 

fingerprint is invisible (Fig. 3A), but the optimal deposition of a chalcogenide-glass CTF on it 

makes it clearly visible (Fig. 3B). The 30 magnified image in Fig. 3C, obtained on an optical 

microscope, shows level-three pore detail. The top-view SEM image at 5000 magnification in 

Fig. 3D is in agreement with the columnar morphology of the CTF deposited atop the latent 

fingerprint (2). Far more convincingly, however, the cross-sectional SEM image at 6000

magnification in Fig. 3E shows not only a generally upward columnar morphology but also the 

conformal shape of the deposited CTF. 

The optimal deposition parameters presented in Table 2 were obtained for just one combination 

of the evaporant material (chalcogenide glass) and the substrate (glass slide). Except for the CTF 

thickness, all other optimal parameters in Table 2 were found to also deliver the best fingerprint 

development for all other combinations of the evaporant material and substrate. However, the 

optimal CTF thickness did depend on the evaporant material. For instance, 50-nm-thick CTFs of 

gold provided optimal contrast, whereas the optimal thickness of a CTF of chalcogenide glass 

turned out to be 20 times higher. For all other combinations of the evaporant material and 

substrate tested, the optimal CTF thickness was found to lie between 50 and 1000 nm, both 

inclusive. 

Meta-analysis of the data collected resulted in the identification of the best evaporant material for 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
22

the CTF development technique as well as the traditional development technique that gave the 

best results for a wide range of non-porous substrates upon which fingerprints are commonly 

found at crime scenes (11,12). The best evaporant material and the optimal CTF thickness––

along with the best traditional technique––for all substrates investigated are provided in Table 3. 

III.1.1.2. Phase II: Comparison with selected traditional development techniques

For several of the substrates investigated, the CTF development technique provided results 

superior to those of all traditional development techniques investigated. For some others, the 

CTF-developed fingerprint and the best traditionally developed fingerprint were of the same 

quality. Both groups of substrates are listed in Table 4, as are the substrates for which the best 

traditional development technique outperformed the CTF development technique. 

Thus, the CTF development technique is not universally applicable, as can be expected from any 

technique to develop latent fingerprints. Development by the deposition of a CTF is suitable 

typically only for non-porous substrates, and the fragility of some substrates poses development 

difficulties. Latent fingerprints on some of the substrates investigated were difficult to develop as 

the temperature within the low-pressure chamber can sometimes reach 40 oC. Some substrates––

such as soft black plastic sheets (black garbage bags)––curled up upon development. In the case 

of Scotch® Duct tape, the cords within the adhesive started pulling out of the substrate of the 

tape. The deformation of some substrates (such as soft plastics and adhesive tapes) inside the 

low-pressure chamber limited the types of evaporant materials that could be used for the CTF 

development of latent fingerprints. In many cases, however, this deformation could be 

minimized by carefully shuttering the source of the thermal energy and minimizing the time that 

the substrate was unnecessarily exposed. 

Some substrates in Table 3 are marked with an asterisk. Whereas the CTF development 

technique did not produce satisfactory results with these substrates, pre-fuming the latent 

fingerprint on these substrates with cyanoacrylate followed by the CTF development technique 

produced the best outcomes. Thus, latent fingerprints on the smooth sides of Scotch® Duct tape 

(Fig. 4) and Gorilla® tape (Fig. 5) developed very well using cyanoacrylate fuming first, 

followed by the deposition of a 50-nm-thick CTF of gold. Quite likely, the successful 

development was facilitated by the layer of cyanoacrylate polymer on the ridge detail, which 

provided better definition of the fingerprint topology, revealed by the CTF deposited on top of 

the enhanced topology. The hybrid cyanoacrylate-CTF technique appears promising and requires 

further research. 

All adhesive tapes were able to withstand the higher than room temperature in the low-pressure 

chamber very well. CTF development with gold as the evaporant material worked very well – 

and better than all traditional development techniques employed – with fingerprints laid on the 

smooth sides of three of the four adhesive tapes investigated. As an example, level-three detail is 

clearly observable in Fig. 6, showing a fingerprint on the smooth side of Gloss Finish Scotch® 

Multitask tape which was developed with a 50-nm-thick CTF of gold. Other substrates, such as 

the smooth sides of Scotch® Duct tape (Fig. 4) and Gorilla® tape (Fig. 5), did require 

application of the hybrid cyanoacrylate-CTF development technique. The sole exception was the 

smooth side of Scotch® Masking tape, for which no development technique delivered a 

satisfactory outcome. 

The CTF development technique also performed well on latent fingerprints on the sticky sides of 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
23

Scotch® Duct tape, Gorilla® tape, and Gloss Finish Scotch® Multitask tape. However, equally 

satisfactory performance was delivered by the traditional development technique of the 

application of WetwopTM, as exemplified in Figs. 7–9. Figure 10 shows that the cyanoacrylate 

fuming (with cyanoblue dye) yielded a superior result on the sticky side of Scotch® Masking 

tape than the CTF development technique. 

The CTF development technique worked very well with latent fingerprints deposited on all three 

types of soft plastics: black garbage bags, white grocery bags, and clear sandwich bags. For 

black garbage bags (Fig. 11) and clear sandwich bags (Fig. 12), the CTF development technique 

provided much better contrast for visualization than any traditional development techniques. 

Even on white grocery bags (Fig. 13), the CTF development technique performed as well as 

dusting with black magnetic powder, the best traditional development technique for the specific 

substrate. 

The CTF development technique did not show superior performance for latent fingerprints on 

hard plastics, the best results obtained with 100-nm-thick CTFs of Alq3. As seen in Figs. 14–17, 

the CTF development technique performed as well as dusting with red fluorescent powder for 

latent fingerprints on black ABS (Fig. 14) and white nylon (Fig. 17). On white ABS (Fig. 15) 

and black nylon (Fig. 16), respectively, dusting with black magnetic powder and red fluorescent 

powder outperformed the CTF development technique. 

Wood substrates are typically porous, except when sealed with a polyurethane or equivalent 

coating. Fingerprints were deposited on smooth substrates of commercial samples of cherry and 

walnut woods that had been stained and sealed. None of the selected evaporant materials worked 

well, with the exception of Alq3. When exposed to short-wave ultraviolet radiation, the Alq3-

developed fingerprints possessed suitable contrast for identification of fingerprint ridge detail. 

None of the chosen traditional methods performed satisfactorily. 

III.1.2. Depleted fingerprint series 

For the depleted fingerprint series, the evaporant materials used included: (i) Alq3, (ii) 

chalcogenide glass of nominal composition Ge28Sb12Se60, (iii) gold, and (iv) nickel. The 

traditional techniques used included: (i) dusting with red fluorescent powder, black powder, and 

white powder; (ii) cyanoblue; and (iii) cyanoacrylate fuming. A hybrid method was also used on 

brass where cyanoacrylate fuming was done before the fingerprint was dusted with black 

powder. The fingerprints subjected to comparative study were the 2nd and the 12th in the 

depletion series. 

Table 5 is a summary of the results. Figure 18 shows the before and after development of 

fingerprints of the depletion series on black ABS. Figure 19 presents a similar example on brass. 

The CTF technique worked well on brass, stainless steel, anodized aluminum, black ABS, and 

white nylon. The CTF technique worked poorly on white ABS and black nylon, but the 

traditional development techniques yielded poor results as well. The sensitivity of the CTF 

technique was greater than of the traditional development techniques on brass and anodized 

aluminum, but similar on stainless steel and all the hard plastics. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
24

III.1.3. Partial bloody fingerprints 

All evaporant materials tested provided satisfactory development of partial bloody fingerprints 

on different substrates, as noted in Table 6. 

An example of CTF development on both the bloody and latent portions of the fingerprint is 

shown in Fig. 20, where the deposition of a 100-nm-thick CTF of nickel developed both the 

patent and the latent portions of a partial bloody fingerprint on stainless steel in a single step. The 

left panel of the figure shows the development resulting from cyanoacrylate fuming followed by 

dusting with regular black powder, which is the traditional technique that gave the best results in 

our laboratory. The CTF development technique clearly performed better. Another example of 

the superior development with the CTF technique over the traditional development techniques is 

shown on brass in Fig. 21. 

Tables 7 and 8 clearly show that the CTF development technique was either superior to or as 

good as traditional attempts to develop partial bloody fingerprints using chemical techniques on 

all substrates tested. Deposition of either a gold CTF or a chalcogenide-glass CTF yielded 

superior results in comparison to those of traditional development techniques, on both hard and 

soft plastics. However, the deposition of gold CTFs performed similarly to traditional 

development techniques on anodized aluminum, and the deposition of nickel CTFs performed 

similarly to traditional development techniques on brass. Deposition of Alq3 CTFs was definitely 

superior to traditional development techniques. Most significantly, the CTF technique was able 

to develop both latent and bloody parts of the fingerprints in one step with good results. 

III.1.4. Discharged cartridge casings 

Discharged cartridge casings have no traditionally accepted method for development of latent 

fingerprints on them, and many of the previously discussed methods have been applied in order 

to find a method with acceptable performance (30). In this study, fingerprints placed on 

cartridge casings before the discharge of a 9 mm Luger from a Ruger P95 pistol were developed 

by the hybrid cyanoacrylate-CTF technique used also for developing latent fingerprints on 

adhesive tapes. 

The fingerprints of two donors were tested. The fingerprints of one donor – whose fingerprints 

were used for most of the work reported here – did not develop at all, whether the CTF technique 

was used or any of the selected traditional techniques was used. However, as can be observed in 

Fig. 22, under short-wave ultraviolet illumination, the developed fingerprint of the second donor 

has sufficient detail for identification. Clearly, the CTF development of fingerprints on 

discharged cartridge casings requires intensive study in the future. 

III.1.5. Fluorescent evaporant materials

CTFs of both fluorescent evaporant materials tested – Alq3 and Eu(tta)3phen – were able to 

develop fingerprints, depending on the substrate. Development with a Eu(tta)3phen CTF was 

superior to development with an Alq3 CTF on white ABS and black nylon, but the reverse was 

true on glass and stainless steel. Figure 23 shows the comparison of the two evaporant materials 

on glass. The left panel shows that development with the Alq3 CTF provides clear details, but 

the right panel shows overdevelopment with the Eu(tta)3phen CTF. 

The development was similar with both evaporant materials on white nylon, black ABS, and 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
25

brass. Both evaporant materials produced clear details, as is clear from Fig. 24 for development 

on white nylon. A summary of all results is provided in Table 9. 

III.1.6. Objective fingerprint grading system 

Although subjective grading, as described in Section II.2.7, was used in the initial 

comprehensive study of Section II.2, the objective grading system, devised by us and described 

in Section II.6, was also used in all subsequent work. The subjective grading system is much too 

coarse in comparison to the devised objective grading system that rated the latent fingerprint in 

Fig. 25 at 2.3% and the cyanoacrylate-fumed fingerprint at 58%. The higher that the objective 

grading, the more is the ridge detail evident in it. The efficacy of the objective grading system in 

relation to actual identification is a topic for further research. 

III.1.7. Preliminary comparison of CTF technique with VMD 

Although both techniques involve the deposition of a material onto latent sebaceous fingerprints 

on a substrate in a vacuum chamber, there are many differences between the two techniques. 

Whereas the film deposited with the CTF technique has a columnar morphology, we found in a 

preliminary comparative study that that the film deposited with VMD comprises islands rather 

than columns, as may be gathered from the cross-sectional SEM images in Fig. 26. 

Using the split-print methodology, we determined that the CTF technique was superior to VMD 

for developing latent fingerprints on clear sandwich bags and partial bloody fingerprints on 

stainless steel. The CTF technique and VMD were similar in their ability to develop latent 

fingerprints on glass but there was more contrast when the CTF technique was used. VMD was 

superior to the CTF technique for developing latent fingerprints on white grocery bags and the 

smooth side of Scotch® Multitask tape. Neither technique worked well for latent fingerprints on 

black garbage bags. A comprehensive comparative study is needed. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
26

III.2. Tables 

TABLE 1––Combinations of forensically relevant substrates and traditional development 

techniques investigated during the initial comprehensive study of Section II.2. 

 

Forensically Relevant 

Substrate Specifically Traditional Development Techniques Studied

Brass Alloy 260 

Regular powder, magnetic 

powder, fluorescent powders, 

cyanoacrylate fuming 

Stainless Steel 420 Grade 

Regular powder, magnetic 

powder, fluorescent powders, 

cyanoacrylate fuming 

Adhesive Tapes (sticky 

and smooth sides) 

Scotch® Duct, Gloss Finish 

Scotch® Multitask, Scotch® 

Masking, Gorilla®

WetwopTM, SSP, SPR, 

cyanoacrylate fuming, 

cyanoblue, powders 

Hard Plastics Nylon, ABS 

Regular powder, magnetic 

powder, fluorescent powders, 

cyanoacrylate fuming 

Soft Plastics Black garbage bag, White 

grocery bag, Clear sandwich bag 

Regular powder, magnetic 

powder, fluorescent powders, 

cyanoacrylate fuming 

Stained and Sealed Woods Cherry, Walnut 

Regular powder, magnetic 

powder, fluorescent powders, 

cyanoacrylate fuming 

Partial Bloody Fingerprints 

on Stainless Steel 

420 Grade 

Regular black powder, LCV, 

amido black, cyanoacrylate 

fuming, cyanoblue 

Discharged Cartridge 

Casing 

9 mm Luger NA

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
27

TABLE 2––Optimized parameters for the deposition of a CTF of chalcogenide glass on a latent 

fingerprint on a glass slide. 

Parameter Values Investigated for 

Optimization 

Optimal Value 

Base Pressure 

(10–4 Torr) 

0.028, 0.13, 1.0, 400 

1.0 

Average Vapor Flux 

Angle 5o, 10o, 15o, 20o, 30o, 60o, 90o 

20o 

CTF Deposition Rate 

(nm s–1) 

0.5, 1.0, 2.0, 5.0

1.0 

Substrate Rotation Rate 

(rpm) 4.5, 15, 60, 180 

180 

CTF Thickness 

(nm) 

200, 500, 800, 1000, 1500, 

2000 

1000 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
28

TABLE 3––The evaporant material employed for the CTF development, the optimal CTF 

thickness, and the traditional technique used for every substrate investigated in the initial 

comprehensive study of Section II.2. The asterisk indicates that the substrate was subjected to 

cyanoacrylate fuming before being subjected to the CEFR method, in order to obtain the best 

CTF development. 

Substrate Evaporant Material 

CTF Thickness 

(nm) 

Traditional 

Development 

Technique 

Brass Chalcogenide Glass 

1000 Black powder/ 

Cyanoacrylate 

Stainless Steel Chalcogenide Glass 

1000 Cyanoacrylate + 

cyanoblue 

Stainless Steel Nickel 

100 Cyanoacrylate + 

cyanoblue 

Stained & Sealed 

Walnut Alq3

100 White magnetic 

powder 

Stained & Sealed 

Cherry Alq3

100 

Black magnetic powder 

Black ABS Alq3

100 Red fluorescent 

powder 

White ABS Alq3 100 Black magnetic powder 

Black Nylon Alq3

100 Red fluorescent 

powder 

White Nylon Alq3

100 Red fluorescent 

powder 

Black Soft Plastic

(Garbage bag) 

Nickel 

100 White magnetic 

powder 

White Soft Plastic 

(Grocery bag) 

Nickel 

100 

Black magnetic powder 

Clear Soft Plastic 

(Sandwich bag) 

Gold 

50 

Cyanoacrylate 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
29

Scotch® Duct Tape – 

sticky side 

Nickel 

100 

WetwopTM 

Scotch® Duct Tape – 

sticky side 

Gold 

50 

WetwopTM 

Scotch® Duct tape – 

smooth side* 

Gold 

50 Cyanoacrylate + 

cyanoblue 

Scotch® Masking tape 

– sticky side 

Nickel 

100 Cyanoacrylate + 

cyanoblue 

Scotch® Masking tape 

– sticky side 

Gold 

50 Cyanoacrylate + 

cyanoblue 

Scotch® Masking tape 

– smooth side 

N/A

N/A

N/A

Gorilla® tape – 

sticky side 

Gold 

50 

WetwopTM 

Gorilla® tape – 

 smooth side* 

Gold 

50 

Cyanoacrylate 

Gloss Finish Scotch® 

Multitask tape – 

 sticky side 

Gold 

50 

WetwopTM 

Gloss Finish Scotch® 

Multitask tape – 

 smooth side 

Gold 

50 

Cyanoacrylate 

Partial Bloody 

Fingerrprint on 

Stainless Steel 

Nickel 

100 

Cyanoacrylate + 

cyanoblue 

Discharged Cartridge 

Casing* Alq3 100 

N/A

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
30

TABLE 4––Comparison of the performances of the CTF development technique and the 

traditional development technique in the initial comprehensive study of Section II.2. The asterisk 

indicates that the substrate was subjected to cyanoacrylate fuming before being subjected to the 

CEFR method, in order to obtain the best CTF development. 

Substrate CTF Development is 

Superior 

Traditional 

Development is 

Superior 

Equal Quality 

Brass - - Yes

Stainless Steel - Yes - 

Stained & Sealed 

Walnut 

Yes - - 

Stained & Sealed 

Cherry 

Yes - - 

Black ABS - - Yes

White ABS - Yes - 

Black Nylon - Yes - 

White Nylon - - Yes

Black Soft Plastic

(Garbage bag) 

Yes - - 

White Soft Plastic 

(Grocery bag) - - Yes

Clear Soft Plastic

(Sandwich bag) 

Yes - - 

Scotch® Duct Tape – 

sticky side - - Yes

Scotch® Duct Tape – 

smooth side* 

Yes* - - 

Scotch® Masking Tape 

– sticky side - Yes - 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
31

Scotch® Masking Tape 

– smooth side - Yes - 

Gorilla® Tape – 

sticky side - - Yes

Gorilla® Tape – 

 smooth side* 

Yes* - - 

Gloss Finish Scotch® 

Multitask Tape – 

 sticky side 

- 

- 

Yes

Gloss Finish Scotch® 

Multitask Tape – 

 smooth side 

Yes 

- 

- 

Partial Bloody 

Fingerprint on Stainless 

Steel

Yes 

- 

- 

Discharged Cartridge 

Casing 

Yes*

N/A - 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
32

TABLE 5––Comparison of the performances of the CTF development technique and traditional 

development techniques for depleted fingerprints on forensically relevant substrates. 

Substrate Development with CTF Evaporant 

Material 

Traditional Development Technique 

Alq3 Chalcogenide 

glass 

Gold Red 

fluorescent 

powder 

Regular 

Powder 

Cyanoacrylat

e fuming with 

cyanoblue 

Black 

ABS 

Poor or 

none 

Small amount Small 

amount 

None Very 

small or 

none 

n/a 

White 

ABS 

Poor or 

none 

No None None None None* 

Black 

Nylon 

Poor or 

none 

Barely any None None Very 

small 

amount 

n/a 

White 

Nylon 

Poor or 

none 

None Small 

amount 

None None n/a 

Stainless 

Steel

n/a Majority n/a n/a n/a Majority 

Anodized 

Aluminum 

Full n/a Barely 

any 

n/a Partial 

faint 

None 

Brass n/a Majority n/a n/a n/a Partial faint * 

*Developed with cyanoacrylate fuming and dusting by black powder 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
33

TABLE 6––Evaporant materials for successful CTF development of partial bloody fingerprints 

on various substrates. 

Substrate CTF Evaporant Material 

Black ABS, White ABS, Black Nylon, White Nylon, Clear Soft 

Plastic, Anodized Aluminum 

Gold 

Black ABS, White ABS, White Nylon, Clear Soft Plastic Chalcogenide Glass 

Black ABS, Black Soft Plastic, White Soft Plastic Eu(TTA)3phen 

White Nylon, Clear Soft Plastic, Brass Nickel 

Brass, Anodized Aluminum Alq3

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
34

Table 7––Comparison of the performances of the CTF development technique and traditional 

development techniques for partial bloody fingerprints on hard and soft plastic substrates. 

Substrate Development with CTF 

Evaporant Material 

Traditional Development Technique 

Chalcogenide 

glass 

Gold Acid Violet 17 Amido Black Powder 

Black 

ABS 

Some and 

faint 

Some or all None Some None 

White 

ABS 

Some and 

faint 

Some or all None Some None 

Black 

Nylon 

n/a Some or all None Some None 

White 

Nylon 

Some and 

faint 

Some or all None Some None 

Clear Soft 

Plastic

Small Some None Some None 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
35

Table 8––Comparison of the performances of the CTF development technique and traditional 

development techniques for partial bloody fingerprints on anodized aluminum and brass. 

Substrate Development with CTF Evaporant 

Material 

Traditional Development Technique 

Alq3 Nickel Gold Fluoroscein Hemascein Powder 

Anodized 

Aluminum 

Full n/a Some 

but faint 

n/a None Some 

Brass Full Some but 

faint 

n/a n/a None Some 

 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
36

Table 9––Comparison of two fluorescent evaporant materials for CTF development of 

fingerprints on forensically relevant substrates. 

 

Substrate Alq3 Eu(tta)3phen Superior 

Development 

White ABS Poor development Poor development Eu(tta)3phen 

Black Nylon No development Some development Eu(tta)3phen 

White Nylon Development but faint Development but faint Equal 

Black ABS Development but faint Development but faint Equal 

Brass Clear development Clear development Equal 

Stainless Steel Clear development No development Alq3

Glass Clear development No development Alq3

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
37

III.3. Figures 

FIG. 1––Illustration of the CTF concept using a toy called Pin Point Impression comprising 

parallel, identical, thin cylindrical pins. Left panel: Pins over a flat surface. Right panel: Pins 

over an undulating surface.

FIG. 2––Schematic of the CEFR method. In a low-pressure chamber, a collimated vapor flux is 

directed towards a substrate mounted on a platform that rotates rapidly about a central normal 

axis. The platform may also be made to rock slowly about an axis lying wholly in the platform 

plane so that the angle between the average direction of the vapor flux and the platform plane

varies periodically, provided the exposed surface of the substrate is significantly lenticular. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
38

FIG. 3––(A) Photograph of a latent fingerprint on a glass slide before CTF development; (B) 

photograph of the developed fingerprint after a 1000-nm-thick CTF of chalcogenide glass had 

been deposited thereon under the optimal conditions identified in Table 2; (C) a 30 magnified 

image on an optical microscope of the developed fingerprint, showing level-three pore detail 

very clearly; (D) top-view SEM image of the developed fingerprint at 5000 magnification; and 

(E) cross-sectional SEM image of a ridge in the developed fingerprint at 6000 magnification. 

FIG. 4––Fingerprint on the smooth side of Scotch® Duct tape developed by a hybrid technique 

involving pretreatment of the latent fingerprint by cyanoacrylate fuming followed by the 

deposition of a 50-nm-thick CTF of gold.

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
39

FIG. 5––Same as Fig. 4, but for the smooth side of Gorilla® tape. 

FIG. 6––Magnified optical image of a fingerprint on the smooth side of Gloss Finish Scotch® 

Multitask tape developed by the deposition of a 50-nm-thick CTF of gold. Pore detail is present 

in the developed fingerprint (arrow). 

FIG. 7––Fingerprint on the sticky side of Scotch® Duct tape developed either (left) by the use of 

WetwopTM or (right) by the deposition of a 100-nm-thick CTF of nickel. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
40

FIG. 8––Fingerprint on the sticky side of Gorilla® tape developed either (left) by the use of 

WetwopTM or (right) by the deposition of a 50-nm-thick CTF of gold.

FIG. 9––Same as Fig. 8, except for the sticky side of gloss finish Scotch® multitask tape. 

FIG. 10––Fingerprint on the sticky side of Scotch® Masking tape developed either (left) by the 

use of WetwopTM or (right) by the deposition of a 100-nm-thick CTF of nickel.

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
41

FIG. 11––Fingerprint on a black garbage bag (soft plastic) developed either (left) by the use of 

white magnetic power or (right) by the deposition of a 100-nm-thick CTF of nickel. Level-three 

detail is clearly seen in the CTF-developed fingerprint. 

FIG. 12––Fingerprint on a clear sandwich bag (soft plastic) developed either (left) by the use of 

cyanoacrylate fuming or (right) by the deposition of a 50-nm-thick CTF of gold. Level-three 

detail is clearly seen in the CTF-developed fingerprint. 

FIG. 13––Fingerprint on a white grocery bag (soft plastic) developed either (left) by the use of 

black magnetic power or (right) by the deposition of a 100-nm-thick CTF of nickel. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
42

FIG. 14––Fingerprint on black ABS developed either (left) by the use of red fluorescent powder 

or (right) by the deposition of a 100-nm-thick CTF of Alq3. Short-wave ultraviolet illumination 

is needed to see the detail in the CTF-developed part of the fingerprint. 

FIG. 15––Fingerprint on white ABS developed either (left) by the use of black magnetic powder 

or (right) by the deposition of a 100-nm-thick CTF of Alq3. Short-wave ultraviolet illumination 

is needed to see the detail in the CTF-developed part of the fingerprint.

FIG. 16––Fingerprint on black nylon developed either (left) by the use of red fluorescent powder 

or (right) by the deposition of a 100-nm-thick CTF of Alq3. Short-wave ultraviolet illumination 

is needed to see the detail in the CTF-developed part of the fingerprint. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
43

FIG. 17––Same as Fig. 16 except that the substrate is white nylon. 

(a) (b) (c) 

(d) (e) (f) 

(g) (h) (i) (j)

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
44

(k) (l) (m) (n)

(o) (p) (q) (r)

FIG. 18––(a-f) Images of the 2nd, 4th, 6th, 8th, 10th, and 12th members of a depleted fingerprint 

series on black ABS before development; (g,I,k,m,o,q) the same sequence of fingerprints 

developed with gold CTF; and (h,j,l,n,p,r) the same sequence of fingerprints developed by 

dusting with white powder. 

(a) (b) (c) (d)

FIG. 19––(a) Second fingerprint in a depleted fingerprint series on brass before development, 

and (b) left side developed with chalcogenide-glass CTF and right side developed with 

cyanoacrylate fuming followed by dusting with black powder. (c) Eighth fingerprint in a 

depleted fingerprint series on brass before development, and (d) left side developed with 

chalcogenide-glass CTF and right side developed with cyanoacrylate fuming followed by dusting 

with black powder. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
45

FIG. 20––Partial bloody fingerprint on 420-grade stainless steel developed either (left) by the use 

of cyanoacrylate fuming followed by dusting with regular black powder or (right) by the 

deposition of a 100-nm-thick CTF of nickel. 

(a) (b) (c)

FIG. 21––(a) Partial blooody fingerprint on brass before development. (b) partial bloody 

fingerprint developed with fluoroscein and green fluorescent powder on brass, and (c) partial 

bloody fingerprint developed with Alq3 on brass. 

FIG. 22––Fingerprint on a bullet casing developed after discharge by a hybrid technique 

involving pretreatment of the latent fingerprint by cyanoacrylate fuming followed by the 

deposition of a 100-nm-thick CTF of Alq3. Short-wave ultraviolet illumination is needed to see 

the detail. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
46

FIG. 23––Fingerprint on glass after the deposition of a CTF of (left) Alq3 and (right) 

Eu(tta)3phen. 

FIG. 24––Fingerprint on white nylon after the deposition of a CTF of (left) Alq3 and (right) 

Eu(tta)3phen. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
47

FIG. 25––(a) Latent fingerprint on Gorilla Tape® before development. (b) Same as (a) but with 

the raw quality map from ULW. (c) Same as (b) but with the quality map darkened prior to 

exporting. (d) Panel (c) after altering the colors in GIMP for input into Mathematica®. (e) 

Latent fingerprint on Gorilla Tape® after development with cyanoacrylate fuming. (f) Same as 

(e) but with the raw quality map from ULW. (g) Same as (f) but with the quality map darkened 

prior to exporting. (h) Panel (g) after altering the colors with GIMP for input into Mathematica®. 

Panels (d) and (h) correspond to 2.3% and 58% area of definitive minutiae, respectively; areas of 

definitive minutiae are indicated as white. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
48

FIG. 26––Cross-sectional SEM images of (a) a zinc film deposited atop a gold film on a 

fingermarked silicon substrate by VMD, (b) a gold CTF deposited on a planar silicon substrate 

by the CTF technique, (c) a fingermark ridge on a silicon substrate conformally coated with a 

nickel CTF, and (d) a fingermark ridge on a glass slide conformally coated with a chalcogenideglass CTF. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
49

IV. Conclusions

 

IV.1. Discussion of findings 

This research project was formulated to ascertain the optimum conditions for CTF development 

of latent sebaceous fingerprints on nonporous forensically relevant substrate. The CTFs were 

deposited using the CEFR technique. Once optimized, the CTF development method was to be 

compared with traditional development methods. 

The results discussed in Section III.1 show that the optimization of CTF development of 

fingerprints on forensically relevant substrates was successful (Table 2). The results also show 

that for laboratory prepared fingerprints, without concern for sensitivity, the CTF development 

method is superior to traditional development techniques for some forensically relevant 

substrates, but for others, a traditional development technique produced a better outcome (Table 

3). The results also show that traditional techniques and CTF were equally good for a few 

substrates (Table 3). 

We also learned that examining and comparing results visually (subjectively) was not 

appropriate for this research because we needed a method that could assess the quality of 

developed fingerprints objectively so that we could effectively and fairly compare different 

development methods. Therefore, we devised a method using the FBI’s ULW, an image 

manipulation software (GIMP) and a program developed in Mathematica® – in order to 

quantitate the minutae as a percentage (Section II.8). The method has the advantage of assessing 

not only the quality of individual fingerprints but also the relative performances of different 

development methods. 

What this research showed was that, under laboratory conditions where sebaceous fingerprints 

were collected to ensure that sufficient fingerprint residue was deposited, CTF development was 

superior for several forensically relevant substrates but not for all. What this research did not 

demonstrate is the capability of CTF technique to develop aged or environmentally stressed 

fingerprints. Also, this research project did not comprehensively compare the CTF technique to a 

somewhat similar technique called VMD; while such a study was not envisaged as part of this 

project, a preliminary comparison was carried out (Sec. III.1.7). 

In a study on depleted fingerprint series, we learned that CTF development of depleted 

fingerprints – to the 12th fingerprint – is equal or superior to the traditional techniques we studied 

(Table 5). 

After comparing the CTF development of partial bloody fingerprints with traditional 

development techniques, we found that the CTF technique is particularly useful for developing 

both the latent and patent areas of such fingerprints in just one development step (Tables 7 and 

8). 

Additionally, the research showed the potential usefulness of a hybrid technque where 

cyanoacrylate fuming and the CTF technique are used in tandem. The hybrid technique showed 

promise for discharged cartridge casings, though this was not an exhaustive study. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
50

Finally, CTFs of two different fluorescent evaporant materials were found to be suitable for 

developing latent fingerprints on different substrates (Table 9). 

It is likely that future research will show that CTF development of latent fingerprints is superior 

to traditional development techniques where the amount of fingerprint residue is limited and for 

fingerprints that are aged, degraded, or exposed to environmentally insulting conditions. Such 

outcomes may emerge, particularly when only a small amount of fingerprint residue is present 

because CTF development relies on the topology of the fingerprint rather than on some physical 

or chemical reaction with the fingerprint residue. 

IV.2. Implications for policy and practice 

Generally, the expected results were obtained, although not as all-encompassing with respect to 

substrates as originally thought. What is clear is that CTF development is a viable technique for 

developing latent fingerprints on difficult substrates. It provides investigators with a viable 

alternative to existing development techniques. And while the equipment is still laboratorybased, there is significant applicability to smaller items of evidence. 

Since bloody fingerprints commonly occur at scenes, CTF development of small items 

containing partial bloody prints is particularly relevant because of the technique’s ability to 

simultaneously develop the latent and patent aspects of the print. Also important may be the use 

of a hybrid technique – cyanoacrylate fuming followed by CTF development – on discharged 

cartridge casings. This is a difficult substrate on which to visualize latent fingerprints. The CTF 

technique shows significant promise, though. 

Problems did occur, however. Highly textured substrates – e.g., textured duct tape – made it 

difficult to obtain results using the CTF technique. Additionally, problems were also encountered 

that occurred because a completely objective system for quantifying the quality of the 

fingerprints developed using the CTF technique and the traditional techniques and for comparing 

results of split fingerprints was needed. This was important because a subjective evaluation was 

considered inappropriate for deciding on the relative performances of the CTF technique and 

traditional development techniques. 

Another problem involved the design and re-work of the low-pressure chamber to handle 

cartridge casings. The curved surface of the cartridge casing had to be taken into consideration 

when the CTF technique was employed to develop latent sebaceous fingerprints. 

IV. 3. Implications for future research

Although the results of this research were largely successful, additional research is required in 

order for the CTF technique to become a routine law enforcement tool. The specific areas that 

require further work follow. 

• Comprehensive comparison of the CTF technique with VMD. Since both techniques are 

similar, a side-by-side comparison is necessary. The CTF technique specifically considers 

development on curved surfaces and also because it deposits a thin film on the ridges of 

the fingerprint compared with VMD that deposits gold in the fingerprint residue followed 

by zinc deposition in the areas outside of the ridges. 

• This research was conducted on ideal, laboratory-prepared, sebaceous-only fingerprints 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
51

that were aged 24 hours. This work needs to be extended to include more reality based 

fingerprints – i.e., fingerprints exposed to various environmental insults (heat, humidity 

and aging). 

• The hybrid technique of cyanoacrylate fuming followed by CTF development of 

fingerprints shows great promise having application to a wide range of forensically 

relevant substrates, specifically discharged cartridge casings. 

• The nature of CTF deposition will allow investigators to ascertain the sequential 

development of fingerprints – which was deposited first? 

• Guidelines need to be developed for specific substrates so that investigators can optimize 

CTF development of latent fingerprints by selectively choosing the appropriate 

evaporants for a specific substrate. 

• Field-forward CTF development equipment is needed. The results of this research 

suggest parameters for such a design that would include simultaneous development on 

multiple items coupled with cyanoacrylate fuming, if necessary. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
52

V. References 

1. Humphries J, Porter G, Bell M. The quantification of fingerprint quality using a relative 

contrast index. Forensic Sci. Int. 2008;178:46-53. Fronthaler H, Kollreider K, Bigun J. 

Automatic image quality assessment with application in biometrics. IEEE Conference on 

Computer Vision and Pattern Recognition Workshop. Volume 2. 2006: June 17-22, pp. 

30-37. Tabassi E, Wilson CL. A novel approach to fingerprint image quality. IEEE 

Conference on Computer Vision and Pattern Recognition Workshop. Volume 2. 2005: 

Sept 11-14, pp. II 37-40. Sears VG, Bleay SM, Bandey HL, Bowman VJ. A 

methodology for finger mark research. Science Justice 2012;2:145-60. 

2. Lakhtakia A, Shaler RC, Martín-Palma RJ, Motyka MA, Pulsifer DP. Solid-state 

acquisition of fingermark topology using dense columnar thin films. J. Forensic Sci. 

2011;56:612-6.

3. Martín-Palma RJ, Pantano CG, Lakhtakia A. Replication of fly eyes by the conformal 

evaporated-film-by-rotation technique. Nanotechnology 2008;19:355704.

4. Martín-Palma RJ, Pantano CG, Lakhtakia A. Biomimetization of butterfly wings by the 

conformal-evaporated-film-by-rotation technique for photonics. Appl. Phys. Lett. 

2008;93:083901.

5. Martín-Palma RJ, Pantano CG, Lakhtakia A. Towards the use of the conformal 

evaporated-film-by-rotation technique in fabricating microelectronic circuits and 

microsystems. Microelectron. Rel. 2009;49:460-2.

6. Pulsifer DP, Lakhtakia A, Martin-Palma RJ. Improved conformal coatings by obliqueangle deposition for bioreplication. Appl. Phys. Lett. 2009;95:193701.

7. Mattox DM. The foundations of vacuum coating technology. Norwich, NY, USA: Noyes 

Publications, 2003.

8. Lakhtakia A, Messier R. Sculptured thin films: nanoengineered morphology and 

optics.Bellingham, WA, USA: SPIE Press, 2005.

9. National Research Council. Summary: Findings and Recommendations. In: Strengthening 

Forensic Science in the United States A Path Forward. The National Academies Press. 

2009:14-33.

10. Ramotowski RS. Chapter 3: Composition of Latent Fingerprint Residue. In Advances 

in Fingerprint Technology 2nd Edition. Eds. Lee RC and Gaensslen RE. CRC Press, 2001 

pp. 63-104.

11. Champod C, Lennard C, Margot P, Stoilovic M. Chapter 4: Fingerprint detection techniques. 

In: Fingerprints and Other Ridge Skin Impressions, CRC Press. 2004.

12. Lee HC and Gaensslen RE. Chapter 4: Methods of latent fingerprint development. In 

Advances in Fingerprint Technology 2nd Edition. Eds. Lee RC and Gaensslen RE. CRC 

Press, 2001 pp. 105-75.

13. Almog J, Azoury M, Elmaliah Y, Berenstein L, Zaban A. Fingerprints’ third dimension: The 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
53

depth and shape of fingerprints penetration into paper – cross section examination by 

fluorescence microscopy. J. Forensic Sci. 2004;49:1-5.

14. Migron Y, Mandler D. Development of latent fingerprints on unfired cartridges by 

palladium deposition: A surface study. J. Forensic Sci. 1997;42:986-92.

15. Watkin JE, Wilkinson D, Misner AG, Yamashita AB. Cyanoacrylate fuming of latent 

prints: vacuum versus heat/humidity. J. Forensic Ident. 1994;44:545-56.

16. Jones N, Mansour D, Stoilovic M, Lennard C, Roux C. The influence of polymer 

type, print donor and age on the quality of fingerprints developed on plastic 

substrates using vacuum metal deposition. Forensic Sci. Int. 2001;124:167-77.

17. Kent T, Thomas GL, Reynoldson TE, East HW. A vacuum coating technique for 

the development of latent fingerprints on polythene. J. Forensic Sci. Soc. 

1976;16:93-101.

18. Home Office Scientific Development Branch. Additional Fingerprint 

Development Techniques for Adhesive Tapes. 2006. Publication No. 23/06.

19. Bond J. Visualization of latent fingerprint corrosion of metallic surfaces. J. Forensic 

Sci. 2008:53:812-22. 

20. Bond J. The thermodynamics of latent fingerprint corrosion of metal elements and 

alloys. J. Forensic Sci. 2008;53:1344-52.

21. Cantu AA, Leben DA, Ramotowski R, Kopera J, Simms JR. Use of acidified 

hydrogen peroxide to remove excess gun blue-treated cartridge cases and to 

develop latent prints on untreated cartridge cases. J. Forensic Sci. 1997;42:294-8.

22. Wargacki SP, Lewis LA, and Dadmun MD. Enhancing the quality of aged latent 

fingerprints developed by superglue fuming: Loss and replenishment of initiator. J. 

Forensic Sci. 2008;53:1138-44.

23. Sears V, Colin G, Butcher PG, Fitzgerald LA. Enhancements of fingerprints in blood 

Part 3: Reactive techniques, Acid Yellow 7 and process sequences. J. Forensic 

Ident. 2005;55:741-63.

24. Kundt A. Ueber Doppelbrechung des Lichtes in Metallschichten, welche durch 

Zerstäuben einer Kathode hergestellt sind. Ann. Phys. Chem. Lpz. 1886;27:59-71.

25. Baumeister, P. W. Optical coating technology. Chap. 9. Bellingham, WA, USA: 

SPIE Press, 2004.

26. Yang B, Walden BL, Messier R, White WB. Computer simulation of the crosssectional morphology of thin films. Proc. SPIE 1987;821:68-76.

27. http://www.alibaba.com/product/jpvaras-105042162- 

101267446/Pin%20Point%20Impression%20Toy.html.

28. http://www.gimp.org

29. http://www.wolfram.com

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
54

30. Migron Y, Hocherman G, Springer S, Almog J, Mandler D. Visualization of 

sebaceous fingerprints on fired cartridge cases: A laboratory study. J Forensic Sci 

1998;43:543-8.

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
55

VI. Dissemination of Research Findings 

• Publications, conference papers, presentations: 

1. S.A. Muhlberger, D.P. Pulsifer, A. Lakhtakia & R.C. Shaler, “Optimized 

deposition of columnar thin films for visualization of latent fingerprints,” 

Nanoelectronic Devices for Defense & Security Conference, Polytechnic Institute 

of New York University, Brooklyn, NY, USA, August 29–September 1, 2011. 

2. S.A. Muhlberger, D.P. Pulsifer, R.J. Martín-Palma, R.C. Shaler & A. 

Lakhtakia, “Optimized deposition of columnar thin films for visualization of 

latent fingerprints,” 39th Annual Symposium of American Society of Crime 

Laboratory Directors, Denver, CO, USA, September 18–22, 2011 (Poster). 

3. D.P. Pulsifer, S.A. Muhlberger, R.J. Martín-Palma, R.C. Shaler & A. 

Lakhtakia, “Optimal conditions for visualization of fingerprints with the 

conformal-evaporated-film-by-rotation technique,” 58th Annual International 

Symposium of American Vacuum Society, Nashville, TN, USA, October 30–

November 4, 2011. 

4. S. Muhlberger, R. Shaler, A. Lakhtakia, D. Pulsifer, & R. Martín-Palma, 

“Visualization of latent fingerprints using columnar thin films,” 64th Annual 

Scientific Meeting of American Academy of Forensic Sciences, Atlanta, GA, USA, 

February 20–25, 2012. 

5. S.F. Williams, R. Shaler, D.P. Pulsifer & A. Lakhtakia, “Visualizing latent 

fingerprints using columnar thin films,” 2012 Annual Meeting of North East 

Association of Forensic Scientists, Saratoga Springs, NY, USA, October 12–17, 

2012. 

6. S.F. Williams, R. Shaler, D. Pulsifer, & A. Lakhtakia, “Visualization of 

depleted latent fingerprints using columnar thin films,” 65th Annual Scientific 

Meeting of American Academy of Forensic Sciences, Washington, DC, USA, 

February 18–23, 2013. 

7. S.A. Muhlberger, D.P. Pulsifer, A. Lakhtakia, R.J. Martín-Palma & R.C. 

Shaler, “Optimized development of sebaceous latent fingermarks on non-porous 

substrates with conformal columnar thin films,” Journal of Forensic Sciences; 

accepted for publication. 

8. D.P. Pulsifer, S.A. Muhlberger, S.F. Williams, R.C. Shaler & A. Lakhtakia, 

“An objective fingerprint quality grading system,” Forensic Science 

International, Vol. 231, pp. 204–207 (2013). 

9. S.F. Williams, D.P. Pulsifer, A. Lakhtakia & R.C. Shaler, “Columnar-thin-filmassisted visualization of depleted latent sebaceous fingermarks on nonporous 

metals and hard plastics,” Journal of Forensic Sciences; currently under review 

for publication. 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.
56

10. S.F. Williams, D.P. Pulsifer, R. C. Shaler & A. Lakhtakia, “Visualization of 

partial bloody fingermarks on nonporous substrates using columnar thin films,” 

Forensic Science International; currently under review for publication. 

• Websites: Nothing to report 

This document is a research report submitted to the U.S. Department of Justice. This report has not 

been published by the Department. Opinions or points of view expressed are those of the author(s) 

and do not necessarily reflect the official position or policies of the U.S. Department of Justice.