1

RDT&E IWG Bloodstain Pattern Analysis Questions

1. What literature exists describing any correlation between the experience/training of an 

individual and an individual’s performance on proficiency testing?

No literature addressing this question has been found.

2. What literature exists that provides a basis for reliably inferring directionality of a 

bloodstain pattern?

Carter, A. L. (2001). "The Directional Analysis of Bloodstain Patterns: Theory and 

Experimental Validation." Journal of the Canadian Society of Forensic Science 34(4): 173-189.

Directional Analysis of bloodstain patterns is a mathematical procedure developed by the 

author that is based on the string method. It finds the directions in space (virtual strings) that 

point from the bloodstains to a spot directly above the location of the blood source. When 

viewed from above, the virtual strings are seen to converge onto the source position. When 

viewed from the side, the virtual strings provide an upper limit for the probable height of the 

blood source. The theory relies only on the well-known physical laws of motion, the resolution 

of a velocity into its three components and simple trigonometry, and does not depend on 

unknown quantities such as droplet sizes and droplet speeds. This procedure has a solid basis in 

physics and mathematics, and satisfies the criterion of sound scientific methodology for 

bloodstain evidence specified by the courts. Digital cameras are used for gathering the evidence 

and the analysis is carried out with a computer. The second part of this paper will describes a 

laboratory experiment that validates "Directional Analysis" both in theory and in practice.
2

Gardner, R. M. (2002). "Directionality in Swipe Patterns." Journal of Forensic Identification

52(5): 579-593.

The author indicates that swipe patterns are very common patterns found within crime scenes. 

The method for determining direction of motion for swipe patterns in bloodstain pattern 

analysis is outlined in numerous references. However these methods have not been previously 

studied or validated. This study identifies five physical characteristics that appear in swipe 

patterns and their orientation in relation to direction of motion. The study suggests that the 

presence of an irregular demarcation in conjunction with any of the other four characteristics in 

the opposite boundary is a valid indicator of direction of motion for the pattern. 

Gross, H. (1924). Traces of Blood. Criminal Investigation: A Practical textbook for Magistrates, 

Police Officers and Lawyers. H. G. J. C. Adam. London, Sweet & Maxwell Ltd. 374-402.

This is a historical document in which the author (Hans Gross) writes about the importance of 

bloodstain letting at a scene. Gross indicates how directionality of blood droplets can be 

determined and explains simple observational experiments that provide understanding of the 

concept. 

Illes, M. B., A. L. Carter, et al. (2005). "Use of the BackTrackTM Computer Program for 

Bloodstain Pattern Analysis of Stains from Downward-Moving Drops." Journal of the 

Canadian Society of Forensic Science 38(4): 213-218.

Using Directional Analysis, the BackTrackTM suite of computer programs can be used to analyze 

a crime scene in which bloodstains only from downward-moving drops are available. Only two 

of three Cartesian coordinates for the blood source location can be accurately determined, but 

this is still significantly better than the stringing and tangent methods, which cannot 

accommodate the stains from downward-moving drops without great difficulty. Crime scene 

investigators with access to this computer program should be aware of the program’s ability to 

use data that cannot be used easily in other methods of analysis. 

Karger, B., R. Nusse, et al. (2002). "Backspatter on the Firearm and Hand in Experimental 

Close-Range Gunshots to the Head." The American Journal of Forensic Medicine and 

Pathology 23(3): 211-213.

The researchers explain the forensic significance of backspatter which is defined as the

“ejection of biological material from the entrance wound in a retrograde direction to the line of 

fire”. This research is based on the reconstruction of back spatter events, providing 
3

information on the directional deposition of biological material (blood) on nearby objects, the 

firearm, hand and arm. 

Karger, B., R. Nusse, et al. (1996). "Backspatter from Experimental Close-Range Shots to the 

Head I-Macrobackspatter." International Journal of Legal Medicine 109: 66-74.

This paper explains the phenomenon of a back spatter event. The authors confirm - by 

observational research - that back spatter exists and has directionality. A blood source was shot 

and the results were documented on white sheets of paper. 

Karger, B., R. Nusse, et al. (1997). "Backspatter from Experimental Close-Range Shots to the 

Head II- Microbackspatter and the Morphology of Bloodstains." International Journal of Legal 

Medicine 110: 27-30.

This paper explains the phenomenon of a back spatter event. The authors confirm - by 

observational research - that back spatter exists and has directionality. This research explores 

the morphology of bloodstains and the distribution of microstains. Microstains are reported to 

be stains with a diameter less than 0.5 mm. 

Knock, C. and M. Davison (2007). "Predicting the Position of the Source of Blood Stains for 

Angled Impacts." Journal of Forensic Sciences 52(5): 1044-1049.

Droplets of pig’s blood were dropped onto paper at different angles to the horizontal to 

produce blood stains. Impact velocities varied from 1.82 to 5.76 m⁄ sec, drop size from 3.7 to 

5.0 mm in diameter, and the surface sloped at angles between 22.7° and 90° to the horizontal. 

From the data a single equation relating stain size to drop size and velocity for all impact angles 

was produced; ab = 111.74 (Re1 ⁄ 2We1 ⁄ 4)0.75DoDo +0.00084 with R2 = 0.88, where a is the 

stain width, b the stain length, Re the Reynolds number, and We the Weber number. A second 

equation related the number of spines, N, to drop size, velocity, and surface slope for all impact 

angles as N = 0.76 We0.5 sin3h with R2 = 0.9, where h is the impact angle. By Ccombining these 

equations the impact velocity can be determined and hence the position of the stain’s source.

Laber, T. L., B. P. Epstein, et al. (2008). "High Speed Digital Video Analysis of Bloodstain 

Pattern Formation From Common Bloodletting Mechanisms." International Association of 

Bloodstain Pattern Analysts News 24 (2): 4-12.

Working on the premise that an understanding of the dynamics of a bloodletting event is 

critical to the sound interpretation of the resultant bloodstain pattern, a set of over 500 
4

individual high speed digital video clips of common bloodletting mechanisms has been 

assembled. These include single blood drop formation, impact spatter, gunshot spatter, 

expiration, cast-off, projected and contact blood staining. These video sequences were 

evaluated to better understand the basic dynamics of bloodletting events. This set of high 

speed video sequences is available for distribution to the forensic science community via the 

Midwest Forensics Resource Center (MFRC) website. The slow motion sequences provide 

evidence of the direction of motion of blood volumes and drops during pattern formation.

MacDonell, H. L. and L. F. Bialousz (1971). "Flight Characteristics and Stain Patterns of Human 

Blood." Law Enforcement Assistance Administration, National Institute of Law Enforcement 

and Criminal Justice: 1-77.

This treatise is one of the first modern day explorations into bloodstain pattern analysis. Mr. 

MacDonell believed that there was a deficiency in bloodstain research and available literature. 

With funding support from the National Institute of Law Enforcement and Criminal Justice he 

researched and reported on the basics of bloodstain pattern analysis. Several chapters were 

dedicated to impact pattern analysis which included target surface characteristics, impact angle 

considerations and spattered blood. This report was one of the first to correlate impact 

patterns, the force applied to the blood source and stain size within the pattern. Furthermore, 

MacDonell advises on the directionality of various blood stain patterns. 
5

3. What is the literature on correction factors for gravity and air resistance when 

determining fluid’s trajectory?

There are hundreds of articles and text books on fluid dynamics. The following articles are a few 

that may help explain Stokes’ Law. 

Hart, F. X. and C. A. Little Iii (1976). "Student investigation of models for the drag force." 

American Journal of Physics 44(9): 872-878.

An experiment is described that allows students to compare the predictions of several models 

for the drag force with observations made in the laboratory. The students can determme

determine the ranges of validity of the Stokes’ law and Newton's law expressions for the drag 

force as well as discover the good agreement with experiment obtained by the numerical 

solutIon of the exact equation of motion. The computer program devised for this purpose can 

be used to simulate the motion of falling objects in situations not directly covered in the 

laboratory.

Luxford, G., D. W. Hammond, et al. (2005). Modelling, Imaging and Measurement of 

Distortion, Drag and Break-up of Aircraft-icing Droplets. 43 rd AIAA Aerospace Sciences 

Meeting and Exhibit Reno, Navada, American Institute of Aeronautics and Astronautics 1-12.

The distortion, drag and break-up of supercooled drizzle droplets in aircraft icing was 

investigated in ambient conditions. An effective efficient computer procedure was developed 

for the distortion and drag of small droplets, < 1mm, at low Reynolds numbers, < 1000, and 

high Weber numbers, > 10. High-speed videos and photographs were obtained with an 

improved high-intensity LED strobe. Experimental measurements validated the drag model for 

droplets distorted by a rapidly accelerating airflow in a convergent wind tunnel. To prevent 

droplet coalescence, due to wake interactions, droplets were generated with a steady jet 

impinging of a rotating slotted disk.

Wierzba, A. (1990). "Deformation and breakup of liquid drops in at nearly critical Weber 

numbers." Experiments in Fluids 9: 59-64.

Experimentally determined values of the critical Weber number available from the literature 

are scattered over a very wide range of We c from 2.2 to 99.6. To study one possible source of 

these discrepancies an experimental investigation was made of the deformation and breakup of 

water droplets at nearly critical Weber numbers. Experiments were conducted in a small 

horizontal wind tunnel. A continuous stream of uniform water droplets was allowed to fall 

perpendicularly to the continuous stream of air. The time histories of water droplets were 
6

recorded by using a high speed camera. Five different basic behaviours of water droplets were 

recorded in the range of We = 11 to 14. It was found that an increase in the Weber number in 

this region resulted in an increased percentage of droplets with regular bag type breakup.

4. What is the literature (from physics or other relevant sciences) that forms the basis for 

knowledge regarding creation of bloodstain patterns? 

There are hundreds of articles that are relevant here. A few are presented. 

Carter, A. L. (2001). "The Directional Analysis of Bloodstain Patterns: Theory and 

Experimental Validation." Journal of the Canadian Society of Forensic Science 34(4): 173-189.

Directional Analysis of bloodstain patterns is a mathematical procedure developed by the 

author that is based on the string method. It finds the directions in space (virtual strings) that 

point from the bloodstains to a spot directly above the location of the blood source. When 

viewed from above, the virtual strings are seen to converge onto the source position. When 

viewed from the side, the virtual strings provide an upper limit for the probable height of the 

blood source. The theory relies only on the well-known physical laws of motion, the resolution 

of a velocity into its three components and simple trigonometry, and does not depend on 

unknown quantities such as droplet sizes and droplet speeds. This procedure has a solid basis in 

physics and mathematics, and satisfies the criterion of sound scientific methodology for 

bloodstain evidence specified by the courts. Digital cameras are used for gathering the evidence 

and the analysis is carried out with a computer. The second part of this paper describes a 

laboratory experiment that validates "Directional Analysis" both in theory and in practice.
7

Laber, T. L., B. P. Epstein, et al. (2008). "High Speed Digital Video Analysis of Bloodstain 

Pattern Formation From Common Bloodletting Mechanisms." International Association of 

Bloodstain Pattern Analysts News 24 (2), 4-12.

Working on the premise that an understanding of the dynamics of a bloodletting event is 

critical to the sound interpretation of the resultant bloodstain pattern, a set of over 500 

individual high speed digital video clips of common bloodletting mechanisms has been 

assembled. These include single blood drop formation, impact spatter, gunshot spatter, 

expiration, cast-off, projected and contact blood staining. These video sequences were 

evaluated to better understand the basic dynamics of bloodletting events. This set of high 

speed video sequences is available for distribution to the forensic science community via the 

Midwest Forensics Resource Center (MFRC) website. It is hoped that the outcome will be a 

significant contribution to the strengthening of the science underpinning bloodstain pattern 

analysis.

Pizzola, P. A., S. Roth, et al. (1986). "Blood Droplet Dynamics- II." Journal of Forensic Sciences

31(1): 50-64.

An earlier companion paper to the present one dealt with a literature review as well as blood 

droplet formation and impacts to stationary target surfaces. The present paper discusses the 

results of experiments with moving target surfaces. These are discussed in the context of their 

correlation with blood droplet impacts to inclined stationary targets and with respect to the 

interpretation of bloodstain patterns at crime scenes where the target surface is capable of its 

own movement. A special belt device was designed and constructed for the experiments 

reported here. This motorized apparatus was used to drive paper belt target surfaces at various 

controlled speeds.

Pizzola, P. A., S. Roth, et al. (1986). "Blood Droplet Dynamics-I." Journal of Forensic Sciences

31(1): 36-49.

The interpretation of bloodstain patterns at crime scenes has received increased attention in 

recent years. Important to an understanding of this is knowledge of the fundamentals of blood 

droplet formation and impact dynamics. A review of the literature reveals that a considerable 

amount of work has been done with aqueous drop dynamics. Workers in the forensic science 

area seem to have been unaware of this. In addition, some of the most important and 

comprehensive early work with blood droplet dynamics seems to have been forgotten. It is not 

cited in more recent publications dealing with bloodstain pattern interpretation. This literature 

is reviewed and discussed as well. The present study presents results of experiments with blood 
8

droplet dynamics and high-speed photographs of blood droplet impacts on stationary target 

surfaces. Some longstanding misconceptions of importance to forensic scientists engaged in 

crime scene reconstruction are discussed.

Raymond, M., E. Smith, et al. (1996). "Oscillating Blood Droplets - Implications for Crime 

Scene Reconstruction." Science & Justice 36(3): 161-171.

Traditionally, the analysis of blood spatter on surfaces in the reconstruction of crime scenes 

relies on the assumption that blood droplets are spherical when they strike the surface. This 

paper explores the effects of their shape on the reconstruction of trajectories from their impact 

pattern, and reports a theoretical analysis of the lifetime of droplet oscillations. Oscillations 

damp quickly in blood droplets due to the viscosity. The analysis provides ranges of velocities 

and distances from the point of droplet projection within which it is unreliable to assume the 

droplets are spherical when they stain a surface. Non-spherical droplet stains predict incorrect 

positioning of the droplet projection point. Experimental data are presented to show that the 

estimates apply in practice.

Raymond, M. A., E. R. Smith, et al. (1996). "The Physical Properties of Blood - Forensic 

Considerations." Science & Justice 36(3): 153-160.

This paper provides a comprehensive description of the usefulness of bloodstain pattern 

analysis at a crime scene. The authors describe possible scenarios where this expertise can be 

applied and the type of information that could be gathered to assist with the reconstruction of 

a crime scene. This includes information such as, the origin of a bloodstain, movement, type of 

pattern, minimum number of blows, order of deposition, damage to victim, deliberate removal 

of bloodstains and direction.
9

Piotrowski, E. (1895). Ueber Entstehung, Form, Richtung und Ausbreitung der Blutspuren 

nach Hiebwunden des Kopfes. Elmira, NY (1992), Golos Printing.

In his paper Piotrowski explains the results of his experiments about the origin, shape, direction 

and distribution of bloodstains after inflicting blunt force trauma. This is a historic scientific 

paper that contains conclusions on Dr. Piotrowski’s experiments and hand drawn colour color 

diagrams of the results. 

Raymond, T. (1997). "Crime Scene Reconstruction from Bloodstains." Australian Journal of 

Forensic Sciences 29(2): 69-78.

Raymond’s paper provides a comprehensive description of the usefulness of bloodstain pattern 

analysis at a crime scene. He describes possible scenarios where this expertise can be applied 

and the type of information that could be gathered to assist with the reconstruction of a crime 

scene. This includes information such as, the origin of a bloodstain, movement, type of pattern, 

minimum number of blows, order of deposition, damage to victim, deliberate removal of 

bloodstains and direction. 

Stephens, B. G. and T. B. Allen (1983). "Back Spatter of Blood from Gunshot Wounds -

Observations and Experimental Simulation." Journal of Forensic Sciences 28(2): 437-439.

It is well known that gunshot wounding can produce fine droplets of blood spatter in a forward 

direction. Under certain circumstances blood droplets can also be propelled backwards in a 

direction against the line of fire. Although the phenomenon of back spatter of blood is most 

commonly seen in contact gunshot wounds of the head, its occurrence is not well recognized. 

In this article the authors summarize investigative and experimental observations concerning 

back spatter writing extensively on directionality. 

5. What literature exists describing the effects of viscosity differences on bloodstain pattern 

analysis conclusions?

Raymond, M., E. Smith, et al. (1996). "Oscillating Blood Droplets - Implications for Crime 

Scene Reconstruction." Science & Justice 36(3): 161-171.

Traditionally, the analysis of blood spatter on surfaces in the reconstruction of crime scenes 

relies on the assumption that blood droplets are spherical when they strike the surface. This 

paper explores the effects of their shape on the reconstruction of trajectories from their impact 

pattern, and reports a theoretical analysis of the lifetime of droplet oscillations. Oscillations 
10

damp quickly in blood droplets due to the viscosity. The analysis provides ranges of velocities 

and distances from the point of droplet projection within which it is unreliable to assume the 

droplets are spherical when they stain a surface. Non-spherical droplet stains predict incorrect 

positioning of the droplet projection point. Experimental data are presented to show that the 

estimates apply in practice.

Raymond, M. A., E. R. Smith, et al. (1996). "The Physical Properties of Blood - Forensic 

Considerations." Science & Justice 36(3): 153-160.

This paper presents a comparison of the physical parameters (surface tension, viscosity and 

density) of aging pig and fresh human blood, under a variety of conditions, as well as 

measurements of droplet trajectories and stain patterns. The results support the use of porcine 

blood (up to two weeks old) in representing the behavior of fresh human blood. The study 

concentrated on blood that was leaving the human body as the viscosity of blood can change 

once outside the human body. Therefore there are limitations as the blood begins to dry or 

clot. 

Thurston, G. B. (1972). "Viscoelasticity of human blood." Biophysical Journal 12.

Measurements made for oscillatory flow of blood in circular tubes show that blood possesses 

elastic properties which make consideration of its viscous properties alone inadequate. Results 

are for a frequency of 10 Hz while varying the amplitude of the velocity gradient for red blood 

cells in plasma at concentrations ranging from 0 to 100% apparent hematocrit. For velocity 

gradients less than 1-2 sec both the viscous and elastic components of the shearing stress are 

linearly related to the gradient. For hematocrits above 20% the elastic component of the 

complex coefficient of viscosity increases with hematocrit approximately to the third power 

while the viscous component increases exponentially. Oscillatory flow measurements at very 

low hematocrits, when extrapolated to zero cell concentration, give the intrinsic viscosity of the 

average individual isolated red cell. The viscous part of this is found to be 1.7 which is 

compared with theoretical values from the rigid ellipsoid model for which the minimum 

possible value is 2.5. This difference is attributed to cell deformability. With increasing velocity 

gradient nonlinear properties develop. The viscous component of the complex viscosity 

becomes of the order of the steady flow viscosity at high gradients while the elastic component 

tends to decrease in inverse proportion to the gradient. Thus, the elastic component of the 

oscillatory stress tends to saturate, this tendency appearing at the approximate level of the 

yield stress.
11

6. What is the literature that demonstrates that certain situational or contextual factors can 

lead to specific “common” patterns of bloodstains and do these hold true across various 

surfaces and textures?

Hulse-Smith, L. and M. Illes (2007). "A Blind Trial Evaluation of a Crime Scene Methodology 

for Deducing Impact Velocity and Droplet Size from Circular Bloodstains." Journal of Forensic 

Sciences 52(1): 65-69.

In a previous study, mechanical engineering models were utilized to deduce impact velocity and 

droplet volume of circular bloodstains by measuring stain diameter and counting spines 

radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate 

the accuracy of this technique, using an applied, crime scene methodology. Calculations from 

bloodstains produced on paper, drywall, and wood were used to derive surface-specific 

equations to predict 39 unknown mock crime scene bloodstains created over a range of impact 

velocities (2.2–5.7 m/sec) and droplet volumes (12–45 mL μL). Strong correlations were found 

between expected and observed results, with correlation coefficients ranging between 0.83 and 

0.99. The 95% confidence limit associated with predictions of impact velocity and droplet 

volume was calculated for paper (0.28 m/sec, 1.7 mL μL), drywall (0.37 m/sec, 1.7 mL μL), and 

wood (0.65 m/sec, 5.2 mL μL).

Karger, B., R. Nusse, et al. (1996). "Backspatter from Experimental Close-Range Shots to the 

Head I-Macrobackspatter." International Journal of Legal Medicine 109: 66-74.

This paper explains the phenomenon of a backspatter event. The authors confirm - by 

observational research - that backspatter exists and has directionality. A blood source was shot 

and the results were documents on white sheets of paper. 

Laber, T. (1985). "Bloodspatter Classification." International Association of Bloodstain Pattern 

Analysts News 2(4): 44-55.

Laber provides an explaintion on the issues surrounding classification of spatter patterns by 

assigning definitions by velocity. He provides an alternative method of identifing bloodstain 

pattterns by stain size and other detail on classification of spatter patterns. 

Laber, T. L., B. P. Epstein, et al. (2008). "High Speed Digital Video Analysis of Bloodstain 

Pattern Formation From Common Bloodletting Mechanisms." International Association of 

Bloodstain Pattern Analysts News 24 (2), 4-12.
12

Working on the premise that an understanding of the dynamics of a bloodletting event is 

critical to the sound interpretation of the resultant bloodstain pattern, a set of over 500 

individual high speed digital video clips of common bloodletting mechanisms has been 

assembled. These include single blood drop formation, impact spatter, gunshot spatter, 

expiration, cast-off, projected and contact blood staining. These video sequences were 

evaluated to better understand the basic dynamics of bloodletting events. This set of high 

speed video sequences is available for distribution to the forensic science community via the 

Midwest Forensics Resource Center (MFRC) website. It is hoped that the outcome will be a 

significant contribution to the strengthening of the science underpinning bloodstain pattern 

analysis.

MacDonell, H. L. and L. F. Bialousz (1971). "Flight Characteristics and Stain Patterns of Human 

Blood." Law Enforcement Assistance Administration, National Institute of Law Enforcement 

and Criminal Justice: 1-77.

This treatise is one of the modern day explorations into bloodstain pattern analysis. Mr. 

MacDonell believed that there was a deficiency in bloodstain research and available literature. 

With funding support from the National Institute of Law Enforcement and Criminal Justice he 

researched and reported on the basics of bloodstain pattern analysis. Several chapters were 

dedicated to impact pattern analysis which included target surface characteristics, impact angle 

considerations and spattered blood. This report was one of the first to correlate impact 

patterns, the force applied to the blood source and stain size within the pattern. Furthermore, 

MacDonell advises on the directionality of various blood stain patterns. 

Piotrowski, E. (1895). Ueber Entstehung, Form, Richtung und Ausbreitung der Blutspuren 

nach Hiebwunden des Kopfes. Elmira, NY (1992), Golos Printing.

In his paper Piotrowski explains the results of his experiments about the origin, shape, direction 

and distribution of bloodstains after inflicting blunt force trauma. This is a historic scientific 

paper that contains conclusions on Dr. Piotrowski’s experiments and hand drawn colour color 

diagrams of the results. 

Pizzola, P. A., S. Roth, et al. (1986). "Blood Droplet Dynamics-I." Journal of Forensic Sciences

31(1): 36-49.

The interpretation of bloodstain patterns at crime scenes has received increased attention in 

recent years. Important to an understanding of this is knowledge of the fundamentals of blood 

droplet formation and impact dynamics. A review of the literature reveals that a considerable 
13

amount of work has been done with aqueous drop dynamics. Workers in the forensic science 

area seem to have been unaware of this. In addition, some of the most important and 

comprehensive early work with blood droplet dynamics seems to have been forgotten. It is not 

cited in more recent publications dealing with bloodstain pattern interpretation. This literature 

is reviewed and discussed as well. The present study presents results of experiments with blood 

droplet dynamics and high-speed photographs of blood droplet impacts on stationary target 

surfaces. Some longstanding misconceptions of importance to forensic scientists engaged in 

crime scene reconstruction are discussed.

Pizzola, P. A., S. Roth, et al. (1986). "Blood Droplet Dynamics- II." Journal of Forensic Sciences

31(1): 50-64.

An earlier companion paper to the present one dealt with a literature review as well as blood 

droplet formation and impacts to stationary target surfaces. The present paper discusses the 

results of experiments with moving target surfaces. These are discussed in the context of their 

correlation with blood droplet impacts to inclined stationary targets and with respect to the 

interpretation of bloodstain patterns at crime scenes where the target surface is capable of its 

own movement. A special belt device was designed and constructed for the experiments 

reported here. This motorized apparatus was used to drive paper belt target surfaces at various 

controlled speeds.

Raymond, T. (1997). "Crime Scene Reconstruction from Bloodstains." Australian Journal of 

Forensic Sciences 29(2): 69-78.

Raymond’s paper provides a comprehensive description of the usefulness of bloodstain pattern 

analysis at a crime scene. He describes possible scenarios where this expertise can be applied 

and the type of information that could be gathered to assist with the reconstruction of a crime 

scene. This includes information such as, the origin of a bloodstain, movement, type of pattern, 

minimum number of blows, order of deposition, damage to victim, deliberate removal of 

bloodstains and direction.

Saviano, J., A. Allgood, et al. (2010). "Using multiple void patterns at crime scenes to estimate 

the area of origin in bloodstain cases." Journal of the Association for Crime Scene 

Reconstruction 16(3): 19-26.

Void patterns in bloodstain pattern analysis are often used to determine the absence or 

movement of an intermediate object from its original position during or after a bloodletting 

event. This article examines the use of void patterns as a method of estimating the area of 
14

origin of events that produce bloodstains. Employment of this method, which the authors have 

termed the Void Pattern Shadow Matching (VPSM) method, can help the analyst or investigator 

at the scene to quickly determine an approximate area of origin, which can later be confirmed 

by mathematical analysis.

White, B. (1986). "Bloodstain Patterns on Fabrics: The Effect of Drop Volume, Dropping 

Height and Impact Angle." Journal of the Canadian Society of Forensic Science 19(1): 3-36.

The authors attempted to determine the relevance of bloodstain patterns on clothing. Two 

different drop volumes were used to passively deposit blood drops on sixteen fabrics at five 

angles and from two different heights. The results indicated if it may in some cases be possible 

to conclude if a bloodstain is consistent with impact spatter or passively falling blood, the 

orientation of the fabric or clothing when blood was deposited and an indication of the 

dropping height. Calculations to determine the angle of impact on most fabrics are not reliable 

and should not be done. In casework applications, blood dropping experiments should be 

conducted on a piece of the fabric being examined when bloodstain pattern interpretation is 

requested. 

7. What literature exists describing the range of patterns possible with expirated blood?

Clark, K. (2006). "Differentiating High Velocity Blood Spatter Patterns, Expirated Bloodstains, 

and Insect Activity." International Association of Bloodstain Pattern Analysis News

(September).

This project examines a difficult area in bloodstain pattern interpretation involving three 

visually and chemically similar stains: high velocity bloodstains due to injury, expirated 

bloodstains, and bloodstains caused by insect activity at the scene. Available literature was 

researched to determine whether each stain type had characteristics with sufficient uniqueness 

to allow differentiation. Articles and textbooks published in bloodstain pattern analysis 

and forensic entomology were utilized to determine the potential for individualizing these 

stains. The project was undertaken to collect relevant data and allow bloodstain pattern 

analysts confronted with stains consistent with high velocity to make the best possible 

classification, and further assist in crime scene reconstruction. By understanding the unique 

characteristics of each bloodstain pattern and the mechanism with which they are 

created, this project seeks to provide a focused collection of the research to date that has 

attempted to differentiate similar stains.
15

Denison, D., A. Porter, et al. (2011). "Forensic implications of respiratory derived blood 

spatter distributions." Forensic Science International 204: 144-155.

The nature of blood aerosols produced in physiological studies of an upright subject expiring 

small volumes through straws, spitting and mouthing sounds, and a semi-prone subject spitting 

through a bloody mouth or snorting through a single nasal orifice and by a simplified physical 

model of the respiratory system were investigated. Each manoeuvre produced many hundreds 

of droplets of a range of size, the vast majority being less than 1 mm diameter. Droplets under 

1 mm dia. travelled over 1 m – much further than could be expected if their flight was ballistic, 

like that of impact spatter. Respired blood aerosol properties are explained in terms of 

established mechanics of airflow shear induced aerosol production and the fluid mechanics of 

exhaled air movement.

Donaldson, A.E., N.K. Walker, I.L. Lamont, S.J. Cordiner, and M.C. Taylor, Characterising the 

dynamics of expirated bloodstain pattern formation using high-speed digital video imaging.

Int J Legal Med 2010.

In this study, high-speed digital video imaging has been used to investigate the formation of 

expirated bloodstain patterns generated by breathing, spitting and coughing mechanisms. 

Bloodstain patterns from all three expiration mechanisms were dominated by the presence of 

stains less than 0.5 mm in diameter. Video analysis showed that in the process of coughing 

blood, high-velocity, very small blood droplets were ejected first. These were followed by lower 

velocity, larger droplets, strands and plumes of liquid held together in part by saliva. The video 

images showed the formation of bubble rings and beaded stains, traditional markers for 

classifying expirated patterns. However, the expulsion mechanism, the distance travelled by the 

blood droplets, and the type of surface the blood was deposited on were all factors 

determining whether beaded stains were generated.

Emes, A. (2001). "Expirated Blood - A Review." Journal of the Canadian Society of Forensic 

Science 34(4): 197-203.

This paper provides a brief review of the literature along with a summary of the properties of 

expirated blood, the mechanisms of production, and the characteristics that may be seen in 

patterns. In 2001, the researcher found little published work on expirated blood. However he

indicates that there are specific characteristics, such as, dilution, blood mixed with saliva, 

mucus or lung surfactant and air bubbles. The patterns may vary significantly in appearance. 
16

Kettner, M., F. Ramsthaler, et al. (2010). ""Bubbles"-A spot diagnosis." Journal of Forensic 

Sciences 55(3): 842-844.

Aspiration of blood is a phenomenon observed in violent and natural death scenarios. 

Bloodstain patterns evolving from expectoration of aspired blood may look suspicious of a 

violent genesis and thus mislead crime scene investigators. In the present case, a woman was 

found lying in a pool of blood on the kitchen floor. Furthermore, bloodstains covered her face, 

clothing, and surrounding furniture and walls. Bloodstain pattern analysis and medicolegal 

inspection of the suspected scene of crime were carried out and revealed dispersed stains with 

enclosed gas bubbles in the absence of signs of physical violence leading to the assessment of a 

natural manner of death. The bloodstains were attributed to expiration of blood because of an 

internal bleeding. Medicolegal autopsy confirmed the on-site diagnosis as a fatal esophageal 

varix rupture was found.

8. What literature exists that quantifies classification of bloodstain patterns?

Karger, B., Rand, S.P., & Brinkman, B. (1998). Experimental Bloodstains on Fabric from 

Contact and from Droplets. International Journal of Legal Medicine 111:17-21.

The authors studied the appearance of similar-size bloodstains on three different types of 

fabrics (bed sheeting, cambric and terry cloth) produced by two different types of mechanisms: 

contact and dynamic or blood dropping. The volume of blood drops used ranged between 0.1 

μl and 10.0 μl. The authors identify four common criteria found for a contact stain which 

reliably allow for classification in most cases (contact versus dynamic) of bloodstains in the 

studied size range. Differentiation between these mechanisms “may be difficult if the fabric 

has a rough and irregular surface structure.” Also, as the stain size decreases, “the differences 

between contact and ‘dynamic’ stains” diminish, so the authors recommend experimentation 

and microscopic comparison of known and unknown bloodstains.

Clark, K. (2006). Differentiating High Velocity Blood Spatter Patterns, Expirated Bloodstains, 

and Insect Activity. International Association of Bloodstain Pattern Analysts News 22 (3), 8-

20. 

This article, a literature review of the three types of patterns included in the title, was 

condensed from a thesis in partial fulfillment for a Master of Forensic Science degree in 2006. 

“The project was undertaken to collect relevant data and allow bloodstain pattern analysts 

confronted with stains consistent with high velocity to make the best possible classification, 

and further assist in crime scene reconstruction.” “This article *examines+ the current literature 
17

and research that has been conducted to attempt to differentiate these types of stains and 

what examinations may provide enough detail to correctly classify them.”

Emes, A. (2001). Expirated Blood – A Review. Journal of the Canadian Society of Forensic 

Science 34 (4): 197-203. 

“The basis of this article was prepared in response to a Quality Assurance trial in the UK, during 

which a number of participating laboratories incorrectly identified a bloodstain pattern that had 

been prepared by coughing blood.” Experiments were done to produce known expirated 

bloodstains patterns demonstrating observed characteristics of expirated blood. Emes offered 

a list of characteristics that could help in the identification of expirated blood. The bloodstains 

under examination must be considered with other circumstances in the case including the 

nature of the surface with the stains and the reported injuries to the subjects involved.

9. What is the literature on the relationship between scene or event bloodstain patterns and 

the accuracy of reconstruction attempts in the laboratory (reproducibility studies)?

Pex, J.O. and Vaughan, C.H. (1987). Observations of High Velocity Bloodspatter on Adjacent 

Objects. Journal of Forensic Sciences 32, No. 6, 1587-1594. 

This study was triggered by the presence of bloodstains on the sleeve cuff of a suspect. The 

authors’ objective was to determine if back spatter on material could be differentiated from 

blood transferred to a material through a light contact mechanism. They reported that 

microscopic examination of the surface receiving the back spatter or light transfer could 

provide the answer to the mechanistic question. They also stated, “*T+his information was 

found to be useful in reconstruction of events in suicides as well as possible homicides.” Also, 

“*A+lthough it (back spatter) may be found as far up the sleeve as the shoulder, it is usually 

limited to the cuff or lower sleeve area . . .”

Pizzola, P.A., Roth, S., and De Forest, P.R. (1986). Blood Droplet Dynamics – II. Journal of 

Forensic Sciences 31, No. 1, 50-64. 

This study involved experiments involving moving target surfaces to examine any correlation 

with blood drops impacting “inclined stationary targets and with respect to the interpretation 

of bloodstain patterns at crime scenes where the target surface is capable of its own 

movement.” The production of bloodstains created at known angles of impact with an inclined 

target surface, a staple in basic bloodstain pattern courses, correlated with an effective angle of 

incidence reported in this study. 
18

Petricevic, S. & Elliot, D. (2005). Bloodstain Pattern Reconstruction – A Hammer Attack. 

Journal of the Canadian Society of Forensic Science 38 (1) 9-19. 

In this homicide case from New Zealand, the victim was struck “at least six times in the back of 

the head with a hammer-like implement.” The defense contended that the assailant’s “clothing 

would have been soaked in blood.” Research was designed and conducted to study the 

reproducibility of impact spatter being present on the assailant’s clothing for the reconstruction 

efforts. Three relative positions of victim and assailant were investigated. The experimental 

results showed that the assailant may have had “very little blood on their clothing” and a lack of 

blood “is not proof of non-involvement.”

Karger, B., Rand, S.P., & Brinkman, B. (1998). Experimental Bloodstains on Fabric from 

Contact and from Droplets. International Journal of Legal Medicine 111:17-21.

The authors studied the appearance of similar-size bloodstains on three different types of 

fabrics (bed sheeting, cambric and terry cloth) produced by two different types of mechanisms: 

contact and dynamic or blood dropping. The volume of blood drops used ranged between 0.1 

μl and 10.0 μl. The authors identify four common criteria found for a contact stain which 

reliably allow for classification in most cases (contact versus dynamic) of bloodstains in the 

studied size range. Differentiation between these mechanisms “may be difficult if the fabric 

has a rough and irregular surface structure.” Also, as the stain size decreases, “the differences 

between contact and ‘dynamic’ stains” diminish, so the authors recommend experimentation 

and microscopic comparison of known and unknown bloodstains. 

Slemko, J.A. (2003). Bloodstains on Fabric: The Effects of Droplet Velocity and Fabric 

Composition. International Association of Bloodstain Pattern Analysts News 19 (4): 3-11. 

The author reports the results of experiments conducted on different types of fabrics, different 

fabric compositions, and condition (new, starched, fabric treatment) with respect to the nature 

of events or mechanisms (contact of liquid blood with the fabric surface with the blood source 

immediately above the fabric and different mechanisms to project blood onto the fabric) and 

the appearance of the resulting stains. Among the reported findings were that both the fabric 

texture and fabric’s ability to absorb blood may distort the appearance of the stain; washing 

affects the stain’s appearance, and fabric treatments need to be considered.
19

White, B. (1986). Bloodstain Patterns on Fabrics: The Effect of Drop Volume, Dropping Height 

and Impact Angle. Journal of the Canadian Society of Forensic Science 19 (1), 3-36.

“The information in this paper has identified some of the limiting factors in the interpretation 

of bloodstains on clothing or fabric items.” “The information gained from *the+ experiments 

may determine whether an opinion on such aspects as the mechanism of production of the 

bloodstains, the position of the fabric when the blood was deposited and the dropping height 

can be expressed.” The author studied a wide variety of fabric types and compositions. “The 

data indicate that calculations of angles of impact on most fabric surfaces examined are not 

reliable and should not be reported.”

Gardner, R.M. (2006). Defining the Diameter of the Smallest Parent Stain Produced by a Drip. 

Journal of Forensic Identification 56 (2), 210-221.

The parameters of this study were three different objects (knife tip, plastic fingernail tip, and 

hypodermic needle) and four surfaces (linoleum, jeans, tile, and carpet) to determine if a 

minimum diameter stain could be determined for passive drop formation. The author 

concluded that “*E+xcluding carpet surfaces, gravity-induced stains (drips) were always greater 

than 4.0 mm. Including the carpet target, the smallest stain was always greater than 3.0 mm.”

Benecke, M., & Barksdale, L. (2003). Distinction of Bloodstain Patterns from Fly Artifacts. 

Forensic Science International 137: 152-159. 

Insect activity at scenes may produce small stains, often referred to as fly specks or fly spots, 

which may introduce confusion into the bloodstain pattern analysis. A laboratory study was 

conducted to examine the stains produced by adult blow flies on vertical paper surfaces. The 

resulting shapes and sizes in conjunction with scene context provided information to help 

differentiate the fly specks from bloodstains at three different scenes (one in the United States 

and two in Germany). Suggestions by the authors to help differentiate stains resulting from 

insect activity and bloodstains related to blood-letting events included documenting the 

presence of flies; noting the locations of small stains with proximity to light sources; 

documenting windows and rooms without a body or blood source; and noting the presence or 

absence of bloodstain pattern characteristics.
20

Fujikawa, A., Barksdale, L., & Carter, D.O. (2009). Calliphora vicina (Diptera: Calliphoridae) 

and Their Ability to Alter the Morphology and Presumptive Chemistry of Bloodstain Patterns. 

Journal of Forensic Identification 59 (5) 502-512. 

For this study, wooden boxes with two glass walls and Plexiglas ceilings were built to observe 

and photograph the activities of flies with respect to their activities involving bloodstains. 

“Experiments were conducted with six contrasting surfaces: painted wall, paneling, wallpaper, 

wood laminate, linoleum, and carpet.” Each experiment was replicated four times. Impact 

spatter and small pools were created using human blood. Flies fed from the edges of the pools 

and the centers of the impact stains. “Feeding activity [of European blue bottle flies] altered 

the shape of many stains, whereas other stains were completely eliminated. Regurgitation and 

defecation *of blood+ resulted in the deposition of multiple new artifacts on all surfaces.” 

“Defecatory artifacts were easily identified by their tailed shape and fluorescence under bluegreen light (465 nm) . . .” Presumptive tests for blood did not differentiate the impact spatter 

from the fly specks.

Striman, B., Fujikawa, A., et al. (2011). Alteration of Expirated Bloodstain Patterns by 

Calliphora vicina and Lucilia sericata (Deptera: Calliphoridae) Through Ingestion and 

Deposition of Artifacts. Journal of Forensic Sciences 56 (S1), S123-S127. 

This study appears to be a continuation of the aforementioned study by Fujikawa, Barksdale, & 

Carter (2009) in the Journal of Forensic Identification, 59 (5) 502-512. Expirated blood instead 

of impact spatter was projected into the boxes. “*T+wo controlled laboratory experiments were 

conducted using various common household wall and floor coverings and two species of flies 

commonly found at scenes of crime.” “Not previously observed was that C. vicina constructed 

artifacts via translocation of expirated bloodstains.” The authors report that “there are no firm 

rules [See Benecke, M., & Barksdale, L. (2003). Distinction of Bloodstain Patterns from Fly 

Artifacts. Forensic Science International, 137: 152-159.] that can be used to differentiate 

artifacts from bloodstain patterns, and it is important not to include or dismiss a stain simply 

because it does not follow dogma. The context of the bloodstain pattern and crime scene must 

be used in analysis.”

Denison, D., Porter, A., Mills, M. & Schroter, R.C. (2011). Forensic Implications of Respiratory 

Derived Blood Spatter Distributions. Forensic Science International 204: 144-155. 

Multiple experiments were conducted to study the “blood aerosols” produced by a variety of 

events with a subject being both upright and semi-prone. The resulting bloodstains, numbering 

in the hundreds, were counted. “Respired blood aerosol properties are explained in terms of 
21

established mechanics of airflow shear induced aerosol production and the fluid mechanics of 

exhaled air movement.” “The flight characteristics of aerosols such as respired blood, 

entrained in the airflow by which they are generated, are fundamentally different from those 

whose ballistic flight is caused by impact or cast off.” “The droplet flight paths cannot be 

predicted in the same way as droplets – such as impact spatter – ejected into still air.”

Emes, A. (2001). Expirated Blood – A Review. Journal of the Canadian Society of Forensic 

Science 34 (4): 197-203. 

“The basis of this article was prepared in response to a Quality Assurance trial in the UK, during 

which a number of participating laboratories incorrectly identified a bloodstain pattern that had 

been prepared by coughing blood.” Experiments were done to produce known expirated 

bloodstain patterns demonstrating observed characteristics of expirated blood. Emes offered a 

list of characteristics that could help in the identification of expirated blood. The bloodstains 

under examination must be considered with other circumstances in the case including the 

nature of the surface with the stains and the reported injuries to the subjects involved.

Karger, B., Nüsse, R., & Bajanowski, T. (2002). Backspatter on the Firearm and Hand in 

Experimental Close-Range Gunshots to the Head. The American Journal of Forensic Medicine 

and Pathology 23 (3), 211-213. 

This backspatter study involved the use of a 9mm pistol and two kinds of ammunition to kill 

nine calves, destined for slaughter, with shooting distances from 0 cm to 10 cm. The firearm, 

surgical gloves and sleeve of the shooter were examined. Backspatter was found on the 

firearm in five of the shots with the number of circular to elongated “droplets” ranging from 2 

to 52. In four of these five instances, a “fine spray of tiny blood droplets was additionally 

present.” Between 1 and 12 droplets were observed in the six instances where droplets were 

found on either or both of the gloves worn at the time of the shooting. In three of these 

shootings, the spray of blood was also reported. Blood was found on the sleeve of the shooting 

hand in four of the cases, with the number of droplets between 1 and 24, with the spray of 

blood in all four instances. Most of these “droplets” were 1 mm to 3 mm in size. The authors 

conclude that “*t+he number and size of the stains can be very small.” Two of the references 

cited were published in 1996 and 1997 by some of the authors.
22

Hulse-Smith, L. & Illes, M. (2007). A Blind Trial Evaluation of a Crime Scene Methodology for 

Deducing Impact Velocity and Droplet Size from Circular Bloodstains. Journal of Forensic 

Sciences 52 (1), 65-69. 

The authors derived surface-specific equations for impact velocities (2.2-5.7 m/sec) and droplet 

volumes (12-45μL) for bloodstains on paper, drywall and wood based on stain diameter and the 

number of radiating spines. “This protocol was then subjected to a blind trial evaluation under 

mock crime scene conditions.” “Strong correlations were found between expected and 

observed results, with correlation coefficients ranging between 0.83 and 0.99.”

Illes, M. & Boue, M. (2011). Investigation of a Model for Stain Selection in Bloodstain Pattern 

Analysis. Journal of the Canadian Society of Forensic Science 44 (1), 1-12. 

The authors present selection criteria for bloodstains to be used to determine an area of origin 

for an impact pattern. The statistical model used for the selection criteria were based on 

impact patterns on vertical surfaces created in the laboratory. They report “zone locations” of 

30° from which impact stains may be selected for measurement and improving the accuracy of 

the area of origin estimation. The results of a validation study are included. While the true 

horizontal distance from a blood source to the vertical surface is not a known on a scene, “it is 

included in the model to account for the increase in error as the distance travelled by the blood 

droplets increases.”

Carter, A.L. (2001). The Directional Analysis of Bloodstain Patterns Theory and Experimental 

Validation. Journal of the Canadian Society of Forensic Science 34 (4), 173-189. 

“Directional Analysis of bloodstain patterns is a mathematical procedure developed by the 

author based on the string method.” It allows the bloodstain pattern analyst with this software 

to determine the “virtual strings” that denote the convergences of the flight paths of the 

bloodstains used to a spot directly above the blood source location. The side view shows an 

upper limit for the blood source’s probable height. Experimental values resulting from the 

computation of the area of origin are in agreement with the known origin.

Illes, M.B., Carter, A.L., et al. (2005). Use of the BackTrackTM Computer Program for 

Bloodstain Pattern Analysis of Stains from Downward-Moving Drops. Journal of the Canadian 

Society of Forensic Science 38 (4), 213-218. 

While bloodstain pattern analysts are taught to use stains created by upward-moving blood 

drops to determine an area of origin for bloodstains on vertical surfaces, this study reports how 
23

stains created by downward-moving drops may be used. The two-dimensional or horizontal 

components of the area of the blood source can still be estimated.

Knock, C. & Davison, M. (2007). Predicting the Position of the Source of Blood Stains for 

Angled Impacts. Journal of Forensic Sciences 52 (5), 1044-1049.

“The experimental work presented in this paper shows that it is possible to use a single 

equation to take into account the impact angle when calculating a blood stain’s size and 

number of spines.” Other data used included the stain’s width and length, the Reynolds 

number, and the Weber number. The parameters in this study were known impact angles from 

22.7° to 90°, drop sizes between 3.7 and 5.0 mm in diameter, and impact velocities between 

1.82 and 5.76 m/sec.

Maloney, A., Nicloux, C., et al. (2011). One Sided Impact Spatter and Area-of-Origin 

Calculations. Journal of Forensic Identification 61 (2), 123-135.

Bloodstain pattern analysts are taught to use the full range of bloodstains (180° area above the 

horizontal plane) for the determination of areas of origin. “This study demonstrates that at 

least some incomplete impact patterns – “one-sided” patterns – need not be eliminated from 

the analysis of the scene because they can still provide an acceptable calculation of the area of 

origin. This study used HemoSpat software for their calculations.

10. What literature exists that describes computer simulations involved in bloodstain pattern 

modeling experiments?

No literature addressing this question has been found.

11. What literature exists regarding the potential for cognitive bias in bloodstain pattern 

analysis including but not limited to confirmatory hypothesis testing (i.e., testing only the 

hypotheses that confirm one’s theory of the event) and the effects of “blinding” 

procedures on examiner conclusions?

No literature addressing this question has been found.
24

12. What is the literature that describes research performed to determine the minimum 

number or threshold of stains required to be present to determine the presence of back 

spatter?

The literature contained references reporting either quantitatively the number of backspatter 

stains found or qualitatively reported qualitatively their presence. None of the literature 

reviewed offered a minimum number or threshold of stains required for determining the 

presence of back spatter. 

Pex, J.O. and Vaughan, C.H. (1987). Observations of High Velocity Bloodspatter on Adjacent 

Objects. Journal of Forensic Sciences 32, No. 6, 1587-1594. 

This study was triggered by bloodstains on the sleeve cuff of a suspect. The authors’ objective 

was to determine if back spatter on material could be differentiated from blood transferred to 

a material through a light contact mechanism. They reported that microscopic examination of 

the surface receiving the back spatter or light transfer could provide the answer to the 

mechanistic question. They also stated, “ . . . because of the elastic nature of the skin, they 

(back spatter bloodstains) may fall from most areas of the shooting hand within minutes.” Also, 

“*T+he observed pattern (backspatter) must not be discounted based on a limited number of 

droplets.”

Betz, P., Peschel, O., Stiefel, D., Eisenmenger, W. (1995). Frequency of blood spatters on the 

shooting hand and of conjunctival petechiae following suicidal gunshot wounds to the head. 

Forensic Science International 76 (1995) 47-53. 

The authors studied 103 suicidal gunshot fatalities and 29 homicidal gunshot fatalities breaking 

them down into categories of type and caliber of firearm. They qualitatively reported the 

percentage of times back spatter was found but did not quantify the data in terms of the 

amount of back spatter bloodstains found. [Their references 1, 3, 11, and 12 were cited for the 

presence of tissue particles or blood spatters on or in the barrel of the weapon as well as on the 

hands of the deceased.]

Stephens, B.G., and Allen, T.B. (1983). Back Spatter of Blood from Gunshot Wounds –

Observations and Experimental Simulation. Journal of Forensic Sciences 28, No. 2, 437-439. 

The authors, both medical doctors working in the office of the San Francisco Medical 

Examiners-Coroner, conducted the study to support the presence of back spatter. Up to that 

time, there was little in the literature on the topic and some experts had claimed that back 
25

spatter did not exist. The authors reported qualitative results supporting the existence of back 

spatter but did not report results quantitatively (amount of bloodstains).

Burnett, B.R. (1991). Detection of Bone and Bone-Plus-Bullet Particles in Backspatter from 

Close-Range Shots to Heads. Journal of Forensic Science 36 (6), 1745-1752.

The author conducted experiments involving the shooting of seven live pigs destined for 

slaughter. He suggests the inclusion of scanning electron microscopy (SEM) coupled with 

energy-dispersive X-ray analysis to identify the elements phosphorus and calcium which were 

present in bone fragments as components of backspatter in addition to blood.

Karger, B., Nüsse, R., & Bajanowski, T. (2002). Backspatter on the Firearm and Hand in 

Experimental Close-Range Gunshots to the Head. The American Journal of Forensic Medicine 

and Pathology 23 (3), 211-213. 

This backspatter study involved the use of a 9mm pistol and two kinds of ammunition to kill 

nine calves, destined for slaughter, with shooting distances from 0 cm to 10 cm. The firearm, 

surgical gloves and sleeve of the shooter were examined. Backspatter was found on the 

firearm in five of the shots with the number of circular to elongated “droplets” ranging from 2 

to 52. In four of these five instances, a “fine spray of tiny blood droplets was additionally 

present.” Between 1 and 12 droplets were observed in the six instances where droplets were 

found on either or both of the gloves worn at the time of the shooting. In three of these 

shootings, the spray of blood was also reported. Blood was found on the sleeve of the shooting 

hand in four of the cases, with the number of droplets between 1 and 24, with the spray of 

blood in all four instances. Most of these “droplets” were 1 mm to 3 mm in size. The authors 

conclude that “*t+he number and size of the stains can be very small.” Two of the references 

cited were published in 1996 and 1997 by some of the authors. [See below.]

Karger, B., Nüsse, R., et al. (1996). Backspatter from Experimental Close-range Shots to the 

Head I. Macrobackspatter. International Journal of Legal Medicine 109: 66-74. 

This article appears to be associated with the preceding article published in 2002. This one 

reported the results of examining bloodstains present “on white paper placed horizontally 60 

cm below the [shooting] impact site. In this report the analysis was restricted to stains with a 

diameter > 0.5 mm.” “The number of stains varied from 31-324 per gunshot.” “The maximum 

distance droplets travelled varied from 72-119 cm.”
26

Karger, B., Nüsse, R., et al. (1997). Backspatter from Experimental Close-range Shots to the 

Head II. Microbackspatter and the Morphology of Bloodstains. International Journal of Legal 

Medicine 110: 27-30. 

This article appears to be associated with the preceding article published in 2002. This one 

reported the results of examining bloodstains present “on white paper placed horizontally 60 

cm below the [shooting] impact site. The morphology of bloodstains and the distribution of 

microstains (diameter < 0.5 mm) is reported.” “The number of microbackspatter stains per 

gunshot varied between 39 and 262 and the maximum travelling distance was 69 cm.”

13. What is the literature that describes the basis for measurement error in directionality 

conclusions?

Directionality for bloodstain pattern analysis falls into at least two categories: the direction of 

travel of blood drops impacting a surface and the examination of the resulting bloodstain to 

ascertain the direction of travel of the drop; second is the direction of motion for events such 

as contacts involving wipes and swipes. No literature addressing this question was found. 

Perhaps reviewing the results of proficiency testing such as that provided by Collaborative 

Testing Services might provide insight.

14. What literature exists regarding the uncertainty of measurement associated with ground 

truth stains (i.e., create elliptic stains for 30° to 60° impact angles stepwise 0.5° at a time 

and determine when one can differentiate the stains)?

Laturnus, P. (1994), “Measurement Survey”. International Association of Bloodstain Pattern 

Analysts News 10(3): p. 14-32.

The author surveyed 27 IABPA members to determine the accuracy of measuring length and 

widths of 10 individual bloodstains for the purposes of estimating angles of impact. He showed 

that many analysts were overestimating angles of impact by overestimating the length of the 

stain. This was particularly a problem for acute angled stains that had tails.

Willis, C., A. K. Piranian, J. R. Donaggio, R. J. Barnett and W. F. Rowe (2001). "Errors in the 

Estimation of the Distance of Fall and Angles of Impact Blood Drops." Forensic Science 

International 123(1): 1-4.

This paper presents derived equations for the estimation of the variances in the estimated 

distance of fall and the estimated angle of impact for blood droplets. The derived equation for 
27

the variance of the estimated distance of fall predicts that as the blood drop size approaches 

that of a blood droplet falling at terminal velocity, the variance of the estimate grows without 

limit. The derived equation for the variance in the estimated angle of impact shows that as the 

angle of impact approaches 90°, the variance grows without limit. The validity of the equation 

for the estimated variance of the angle of impact was tested for five angles of impact (15, 30,

45, 60 and 75°); the equation correctly predicted the observed variance up to an angle of 60°.

Pace, A. (2005). "The Relationship between Errors in Ellipse Fitting and the Increasing Degree 

of Error in Angle of Impact Calculations." International Association of Bloodstain Pattern 

Analysts News 21(3): 12-14.

This paper considered the error in angle of impact calculation which is rendered by a 1 

millimeter error in the measurement of bloodstain lengths. This error was practically negligible 

up to impact angle of around 50°, thereafter it increased rapidly. Similar calculations made 

with other bloodstain width/length ratios will yield different degrees of error, however the 

general trend will be the same – the greater the impact angle of a bloodstain, the greater will 

be the result of a measurement error.

Reynolds, M., D. Franklin, M. A. Raymond and I. Dadour (2008). "Bloodstain measurement 

using computer-fitted theoretical ellipses: A study in accuracy and precision." Journal of 

Forensic Identification 58(4): 469-484.

This paper describes an accuracy and precision study conducted on two methods of computerassisted ellipse fitting (BackTrackTM Images and the newly developed Microsoft Office Excel 

2003 AutoShapes) for bloodstain measurement purposes. The study, conducted in known and 

blind environments, demonstrated both methods of computer-assisted ellipse fitting to be 

robust and reliable bloodstain measurement techniques, particularly for those stains that have 

obliquely impacted a planar surface.

15. What is the literature that demonstrates the reliability (intra- and inter-examiner) of 

pattern classification? What is the literature that demonstrates the reliability (intra- and 

inter-examiner) of determining the cause of a "void"? 

No literature addressing this question has been found.
28

16. What is the literature regarding the establishment of error rates associated with 

conclusions offered by bloodstain pattern analysts? 

Liesegang, J. (2004). "Bloodstain Pattern Analysis - Blood Source Location." Journal of the 

Canadian Society of Forensic Science 37(4): 215-222.

This paper focuses on the useful, well-known paper by Carter and Podworny which describes a 

procedure for calculating the horizontal planar position (taken as the X-Y plane) or plan position 

of the source as a point (X, Y), these being the plan co-ordinates of the vertical line of 

intersection of the vertical trajectory planes associated with two droplet stains. Elementary 

calculus is applied to equivalent expressions to those of Carter and Podworny for X and Y, 

allowing in a well-defined way, the calculation of quotable uncertainties or errors in X and Y; 

i.e., the positive and negative values of which specify the precision limits of the calculated X and 

Y values. To illustrate the way in which these uncertainties may vary with distance and with 

angular position with respect to selected stains, a visualization of this precision is also 

presented.

Carter, A. L., et al. (2005). "Further Validation of the BackTrack TM Computer Program for 

Bloodstain Pattern Analysis - Precision and Accuracy." International Association of Bloodstain 

Pattern Analysts News 21(3): 15-22.

In this work, 18 bloodstain targets were created, and then analyzed independently by a number 

of trained bloodstain pattern analysts (N = 8-11) using the BackTrackTM programs. The results 

indicate high precision, demonstrating that a number of investigators, analyzing the same 

scene, will arrive at approximately the same result with the program. The standard deviations 

for the X-, Y-, and Z-values for all 18 patterns were very small, ranging from 0.46 to 7.02 cm, 

with the majority (44/54) being less than 3 cm. 

Carter, A. L., J. Forsythe-Erman, V. Hawkes, M. Illes, P. Laturnus, G. Lefebvre, C. Stewart and 

B. Yamashita (2006). "Validation of the BackTrackTM Suite of Programs for Bloodstain Pattern 

Analysis." Journal of Forensic Identification 56(2): 242-254.

122 impact spatter patterns were analyzed by students on various bloodstain pattern courses 

using the BackTrackTM software to determine blood source location. The average difference 

from the true source location was 4.23 cm , 3.15 cm and 6.25 cm for X, Y, Z coordinates 

respectively.
29

Rowe, W. F. (2006). "Errors in the Determination of the Point of Origin of Bloodstains." 

Forensic Science International 161(1): 47-51.

This paper extends the derivations in the Liesegang study work by expressing the uncertainties 

in the coordinates of the point of origin of two bloodstains in terms of the uncertainties in the 

length and width measurements from which the angles of impact of the bloodstains are 

calculated.

Reynolds, M. E., M. A. Raymond and I. Dadour (2009). "The use of small bloodstains in blood 

source area of origin determinations." Journal of the Canadian Society of Forensic Science

42(2): 133-146.

Due to the increased likelihood of manual measurement error, small bloodstains (≤ 3.0mm 

long) have rarely been used in three-dimensional blood source area of origin determinations. 

The advent of computer assisted measurement methods, offering improved levels of accuracy 

and precision, broadens the range of bloodstain sizes available for selection to determine a 

blood source area of origin. With inertia, viscosity and surface tension playing important, yet 

competing, roles in bloodstain formation, the power law relationships that exist between 

droplet volumes, droplet diameter, and bloodstain width suggest possible non-agreement 

between experimentally calculated angle of impact values when compared against those values 

theoretically expected. In order to compare experimental angle of impact calculation trends 

with angle of impact calculation theory, this study examined small bloodstains created by blood 

drops falling vertically onto surfaces offset from the vertical and small bloodstains generated by 

impact events subsequently deposited on adjacent vertical surfaces. This study shows that an 

apparent power law relationship may exist between the size of a parent blood droplet and the 

role of viscous and surface tension forces on subsequent bloodstain formation, particularly on 

those bloodstains caused by small droplets impacting obliquely with planar surfaces.

17. What is the literature that describes any divergence of interpretations offered by

 bloodstain pattern analysts? 

No literature addressing this question has been found.
30

18. What is the literature describing any research focused on developing techniques for aging 

 bloodstains or developing bloodstains on dark surfaces?

18.1 Aging of blood

Funao T., Maeda I (1959) Studies on the determination of the age of bloodstains. Jpn J Leg 

Med 13: 735–740.

no abstract available

Kind, S. S., D. Patterson and G. W. Owen (1972). "Estimation of the age of dried blood stains 

by a spectrophotometric method." Forensic Science 1(1): 27-54. 

The visible absorption spectra of dried blood samples were examined and a time and 

temperature dependent quantity called the “a ratio” derived. This parameter is independent of 

the amount of blood present and its determination can provide useful assistance in estimating 

the age of a bloodstain. 

Kind, S. S. and M. Watson (1973). "The estimation of blood stain age from the 

spectrophotometric properties of ammoniacal blood stain extracts." Forensic Science 2(0): 

325-332.

The visible absorption spectra of a series of blood stains up to 15 years old were examined and 

found to vary in a regular manner with age. A quantity called the “αs ratio” has been derived 

and calculated for all bloodstains examined. It was suggested that this parameter can give a 

useful indication of blood stain age up to periods of 10–15 years after stain formation. 

Rajamannar, K. (1977). "Determination of the age of bloodstains using 

immunoelectrophoresis." Journal of Forensic Sciences 22(1): 159-164.

The technique of immunoelectrophoresis was used to determine the age of bloodstains. The 

immunoelectrophoretic patterns (IEP) of bloodstains ranging from 15 days to one year old were 

obtained by the use of high titer anti-whole human serum. The IEPs revealed gradual 

disappearance of beta-globulins and gamma-globulin with increase in the age of bloodstains. A 

comparative study of the IEP of normal human serum with those of the experimental 

bloodstains showed the absence of some of the corresponding proteins. The absence of a 

particular serum protein in the IEP of a given bloodstain will indicate the age of that bloodstain.
31

Sakurai, H., K. Tsuchiya, Y. Fujita and K. Okada (1989). "Dating of human blood by electron 

spin resonance spectroscopy." Naturwissenschaften 76(1): 24-25.

no abstract available

Inoue, H., F. Takabe, M. Iwasa and Y. Maeno (1991). "Identification of fetal hemoglobin and 

simultaneous estimation of bloodstain age by high-performance liquid chromatography." 

International Journal of Legal Medicine 104(3): 127-131. 

A method using reverse-phase high-performance liquid chromatography (HPLC) for the 

identification of fetal hemoglobin (Hb F) and the simultaneous estimation of bloodstain age is 

described. Umbilical cord and neonatal bloodstains can be differentiated from adult stains by 

the presence of -globin chains which are characteristic of Hb F. With this method, cord and 

neonatal blood could be distinguished from adult blood in stains up to 32 weeks old. The age of 

the stain was estimated from the ratio of the peak area of the -globin chain to that of heme 

on the same chromatogram. The ratio decreased gradually with an increase in the age of the 

stain up to 20 weeks old. Studies performed at each time period revealed no significant 

difference in the ratios of cord and neonatal bloodstains or in the ratios of cord and adult 

stains. The regression equation calculated from the ratios ( y ) and the ages of stains in weeks 

(x ) expressed logarithmically is y = 2.5758 - 0.2497 ln( x ) and the coefficient of correlation is -

0.7491 ( n = 252, P < 0.001). 

Inoue, H., F. Takabe, M. Iwasa, Y. Maeno and Y. Seko (1992). "A new marker for estimation of 

bloodstain age by high performance liquid chromatography." Forensic Science International

57(1): 17-27

The applicability of a marker for estimation of bloodstain age by reverse-phase high 

performance liquid chromatography (HPLC) is described. Using a μBondasphere C18 column 

with a two step linear gradient of 10.5–46.25% acetonitrile in 0.1% trifluoroacetic acid, an 

intriguing peak (unidentified) at a retention time of about 5 min was observed on 

chromatograms from human adult bloodstains and designated as ‘X’. The area of this peak, 

which could be detected in extracts of bloodstains, but not in their fresh whole blood, increased 

with time. The ratios of the X area to heme area in bloodstains stored at room temperature and 

4°C for up to 52 weeks old linearly correlated with stain age by plotting on a double logarithmic 

scale. In bloodstains exposed to fluorescent light at room temperature, the regression equation 

calculated from the ratios (Rx) and the ages of stains in weeks (W) is ln(1000 · Rx) = 1.1084 + 
32

0.3937 · ln(7 · W), and the coefficient of correlation (r) is 0.9776 (n = 144, P < 0.001). When 

stains were stored at 37°C, the ratio transformed into logarithms correlated linearly with stain 

age. The regression equation describing the relationship in bloodstains exposed to fluorescent 

light at 37°C is ln(1000 · Rx) = 2.4477 + 0.0866 · W (r = 0.9826, n = 144, P < 0.001). The results 

of suggest that the HPLC method may be applicable to the estimation of bloodstain age.

Kumagai, R. (1993). "Analysis of hemoglobin in bloodstains using high-performance liquid 

chromatography." Nihon Hoigaku Zasshi 47(3): 213-219

Hemoglobin (Hb) extracted from bloodstains was investigated using cation-exchange highperformance liquid chromatography (HPLC). Among the HbA1 fractions, the amount of HbA1d 

increased linearly as the ages of the bloodstains increased, although the amount of HbA1c 

remained virtually unchanged. As HbA1 fractions are Hb modified with glucose or glycolytic 

intermediates, the total Hb were separated into glycated and non-glycated Hb fractions using 

affinity chromatography to investigate the effects of glucose on the age-induced Hb changes. 

The amounts of glycated Hb increased in proportion to the blood glucose level, and the 

increased glycated Hbs were eluted at retention times that corresponded to those of HbA1d 

and HbA0, although HbA1c peak area was virtually unchanged. The amounts of both glycated 

and non-glycated HbA1d increased with bloodstain aging, and the proportion of non-glycated 

HbA1d relative to the total HbA1d was greater than that of glycated HbA1d. These findings 

showed that glucose has little effects on the elevation of HbA1d in bloodstains that occurs as 

they age. Furthermore, measuring HbA1d levels in bloodstains using HPLC may prove useful for 

the determination of their ages.

Matsuoka, T., T. Taguchi and J. Okuda (1995). "Estimation of bloodstain age by rapid 

determinations of oxyhemoglobin by use of oxygen electrode and total hemoglobin." Biol 

Pharm Bull 18(8): 1031-1035.

Bloodstain age was estimated from the ratio of oxyhemoglobin/total hemoglobin (fractional 

oxyhemoglobin) in the bloodstain if the temperature at which the bloodstain had been kept 

was known. The oxyhemoglobin was determined with an oxygen electrode immersed in water 

in which the oxygen had been depleted, and the total hemoglobin was determined by 

conventional colorimetry (cyanomethemoglobin method). Ages of prepared bloodstain samples 

(within 24 h after bleeding) were estimated by this present method, which requires only 20 

microliters of bloodstain and only 5 min for the whole analysis.
33

Andrasko, J. (1997). "The estimation of age of bloodstains by HPLC analysis." Journal of 

Forensic Sciences 42(4): 601-607. 

This paper describes an HPLC system for estimating the age of bloodstains deposited on 

clothing. In addition to the decomposition peak designated as "X", several other ageing 

processes were studied and found suitable for estimation of age of the stains. The various 

processes can be used independently of each other for estimation of bloodstain age when the 

storing temperature is known. Moreover, the ratio between the different peaks formed by 

ageing is practically independent of temperature between 0 degree C and 37 degrees C.

Bauer, M., S. Polzin and D. Patzelt (2003). "Quantification of RNA degradation by semiquantitative duplex and competitive RT-PCR: a possible indicator of the age of bloodstains?" 

Forensic Science International 138(1-3): 94-103

In vitro RNA degradation is a complex and non-linear process which can serve as indicator for 

the quality and age of stains. The authors report a semi-quantitative duplex reverse 

transcription-polymerase chain reaction (RT-PCR) assay which, in combination with competitive 

RT-PCR using an external standard, allows quantification of RNA degradation levels. Using this 

method, 106 bloodstains stored up to 15 years were investigated. The distribution of the peak 

area quotients of standard and target messenger-RNA (mRNA) as measured by laser-induced 

fluorescence capillary electrophoresis was closely correlated with the age of the samples. 

Further statistical analysis showed that bloodstains with age differences of 5 years and more 

exhibit statistical significant variances in peak area quotients of both housekeeping genes 

included in this study, β-actin and cyclophilin. Although RNA continues to be degraded in dried 

bloodstains, mRNA suitable for RT-PCR can be isolated from samples stored for at least 15 

years.

Anderson, S., B. Howard, G. R. Hobbs and C. P. Bishop (2005). "A Method for Determining the 

Age of a Bloodstain." Forensic Science International 148: 37-45.

The authors report the use of a real-time reverse transcriptase PCR to show that the ratio 

between different types of RNA (mRNA versus rRNA) changes over time in a linear fashion 

when dried human blood from eight individuals was examined over the course of 150 days. This 

approach reportedly offers the advantages of enhanced detectability of small samples, 

simultaneous isolation of DNA and RNA from the same sample, species-specific probes, and an 

increased time window of usefulness.
34

Fujita, Y., K. Tsuchiya, S. Abe, Y. Takiguchi, S. Kubo and H. Sakurai (2005). "Estimation of the 

Age of Human Bloodstains by Electron Paramagnetic Resonance Spectroscopy: Long-term 

Controlled Experiment on the Effects of Environmental Factors." Forensic Science 

International 152: 39-43.

In this study, the efficacy and limitations of electron paramagnetic resonance (EPR) for 

estimating the age of human bloodstains was investigated. At 77 K, human bloodstains give 

four striking EPR signals in the g = 6.2 (g6), 4.3 (g4), 2.27 (H) and 2.005 (R) regions due to ferric 

high-spin, ferric non-heme, ferric low-spin and free radical species, respectively. Plotting double 

logarithms of the EPR intensity ratio of H/g4 versus days past bleeding gave a linear correlation 

up to 432 days with an error range within 25% of the actual number of days under controlled

conditions. However, environmental factors such as differences of absorbent, light exposure 

and fluctuations of storage temperature affected the changes of these EPR-active compounds, 

which result in miss-estimation of the time since bleeding occurred. 

Strasser, S., A. Zink, G. Kada, P. Hinterdorfer, O. Peschel, W. M. Heckl, A. G. Nerlich and S. 

Thalhammer (2007). "Age determination of blood spots in forensic medicine by force 

spectroscopy." Forensic Science International 170(1): 8-14.

The authors report a method for the estimation of the age of bloodstains using atomic force 

microscopy (AFM) for high-resolution imaging of erythrocytes in a blood sample and the 

detection of elasticity changes on a nanometer scale. In the analytic procedure a fresh blood 

spot was applied to a glass slide and AFM detection is started after drying of the blood drop. In 

a first step, an overview image was generated showing the presence of several red blood cells, 

which could easily be detected due to their typical "doughnut-like" appearance. The 

consecutively morphological investigations in a timeframe of 4 weeks could not show any 

alterations. Secondly, AFM was used to test the elasticity by recording force-distance curves. 

The measurements were performed immediately after drying, 1.5 h, 30 h and 31 days. The 

conditions were kept constant at room temperature (20°C) and a humidity of 30%. The 

obtained elasticity parameters were plotted against a timeline and repeated several times. The 

elasticity pattern showed a decrease over time, which are probably influenced by the alteration 

of the bloodstain during the drying and coagulation process. The preliminary data 

demonstrated the capacity of this method to use it for development of calibration curves, 

which can be used for estimation of bloodstain ages during forensic investigations.
35

Hanson, E. K. and J. Ballantyne (2010). "A blue spectral shift of the hemoglobin soret band 

correlates with the age (time since deposition) of dried bloodstains." PLoS One 5(9): e12830.

The authors report a method for the estimation of the time since deposition (TSD) of dried 

bloodstains using UV-VIS spectrophotometric analysis of hemoglobin (Hb) that is based upon its 

characteristic oxidation chemistry. A detailed study of the Hb Soret band (lambdamax=412 nm) 

in aged bloodstains revealed a blue shift (shift to shorter wavelength) as the age of the stain 

increases. The extent of this shift permits, for the first time, a distinction to be made between 

bloodstains that were deposited minutes, hours, days and weeks prior to recovery and analysis. 

The extent of the blue shift was found to be a function of ambient relative humidity and 

temperature. The method is reportedly extremely sensitive, requiring as little as a 1 microliter 

of dried bloodstain for analysis. The authors demonstrate that it might be possible to perform 

TSD measurements at the crime scene using a portable low-sample-volume 

spectrophotometer.

Anderson, S. E., G. R. Hobbs and C. P. Bishop (2011). "Multivariate Analysis for Estimating the 

Age of a Bloodstain*." Journal of Forensic Sciences 56(1): 186-193.

The authors report a multiplexed, real-time RT-PCR (or qPCR) method to determine the relative 

stability of different-sized segments of the same RNA species as well as differences in stability 

between two different RNAs’ change over time in bloodstains. Their results indicate that a 

multivariate analysis of the changing ratio of the different RNA segments can be used to 

differentiate between samples of different ages in the defined population. Bloodstains from 29 

of 30 donors were partitioned into different ages using this technique. Although further 

improvements will be required before this approach can be implemented in crime laboratories, 

the multivariate analysis holds promise of providing a reliable approach for temporally linking a 

bloodstain to the commission of a crime or excluding a bloodstain as being irrelevant to the 

case in question.

Bremmer, R. H., K. G. de Bruin, M. J. C. van Gemert, T. G. van Leeuwen and M. C. G. Aalders 

"Forensic quest for age determination of bloodstains." Forensic Science International (in 

press)

This review gives an overview of an extensive search in scientific literature of techniques that 

address the quest for age determination of bloodstains. The authors report that most 

techniques are complementary to each other, in short as well as long term age determination. 

Techniques are compared concerning their sensitivity for short and long term ageing of 

bloodstains and concerning their possible applicability to be used on a crime scene. In addition, 
36

experimental challenges like substrate variation, interdonor variation and environmental 

influences are addressed. Comparison of these techniques contributes to our knowledge of the 

physics and biochemistry in an ageing bloodstain. Further improvement and incorporation of 

environmental factors are necessary to enable age determination of bloodstains to be 

acceptable in court.

18.2 Dark Surfaces

Bergeron, J. (2003). "Development of Bloody Prints on Dark Surfaces with Titanium Dioxide 

and Methanol." Journal of Forensic Identification 53(2): 149-161.

no abstract available

19. What new technologies and areas of research should be pursued with regard to 

bloodstain pattern analysis? (Note- this question does not require a list of references, it is for 

informational purposes only.)

The following list represents the current research needs developed and agreed to by 

participants of the SWGSTAIN. The document is intended to focus research efforts on the most 

pertinent open questions within the discipline. It is neither exclusive nor prescriptive but rather 

indicative of current needs. No specific priority is intended by the order of this list. 

1. Research that would minimize ambiguity in the characterization of small stain blood 

spatter patterns 

Blood spatter patterns consisting of small stains created by different mechanisms can appear 

similar. Research is needed to develop methods that provide more discrimination between 

these patterns.

2. Research to evaluate the behavior of blood on fabric surfaces

BPA investigations frequently involve the examination of bloodstained clothing. Research is 

needed to develop an understanding of the complex problems of how blood transfers to, 

interacts with and persists on fabric surfaces.
37

3. Research to develop new methods to assist with the visualization of bloodstains on difficult 

surfaces

Without the use of enhancement techniques bloodstains can be difficult to visualize, especially 

on dark surfaces. Research is needed to develop and validate specialized techniques to locate, 

enhance and record bloodstains.

4. Research to develop new automated methods to record bloodstain patterns at crime 

scenes

The current manual methods of recording bloodstain data at crime scenes are time consuming, 

resource intensive and potentially subjective. Research is needed to implement new 

technologies and methods that would minimize subjectivity and maximize the amount of data 

that can be collected.

5. Research to determine the extent of bias in bloodstain pattern analysis

It is acknowledged that bias exists within forensic science, including bloodstain pattern analysis. 

Research is needed to determine what biases exist. Methods to identify, quantify and minimize 

such biases are required.

6. Research to develop methods to determine the age of bloodstains

Currently there are no validated methods to determine the age of a bloodstain. Research is 

needed to determine the factors that are relevant to the aging of a bloodstain and to develop 

reliable methods to determine a bloodstain’s age. 

7. Research to correlate bloodstain patterns at a crime scene with those on involved parties

Arguments in court often centre on the quantity of blood on relevant individuals, in particular 

defendants. It is known that the extent of bloodshed at a scene may not obviously correlate 

with the blood deposited on involved parties, their clothing and other items. Research is 

needed to develop an understanding of the distribution of blood during bloodletting incidents 

to assist the court with determining the extent of involvement of relevant individuals.
38

8. Research to develop new methods to simulate human blood, tissue and body parts to 

assist with reconstruction experiments

Experiments to investigate bloodstain pattern formation are limited by difficulties in simulating 

bloodletting events using human subjects. Research is needed to develop standard simulant 

materials to assist with physical and numerical modeling experiments.

9. Research to develop quantitative computer models for bloodstain pattern reconstruction

Experiments to test specific crime scene hypotheses and fundamental research into the 

complexity of bloodstain pattern formation are frequently expensive, time consuming, have 

health and safety implications and require ethical approval. Research is required to assess 

current numerical models and develop new quantitative computer models for bloodstain 

pattern reconstruction. These will require robust data sets derived from evidence examination 

and laboratory experimentation.

10. Research to develop reliable means of sequencing overlapping patterns.

Determining the sequence in which bloodstains were deposited can be difficult. Currently 

there are no established, validated methods by which this can be done. Research is required to 

develop methods to address this problem.

11. Research to determine the effect of the variation in blood composition on bloodstain 

pattern formation

Currently little is known about the effect of the variation in blood composition on the formation 

and appearance of bloodstain patterns. Research is required to determine the influence of 

drugs, medical conditions, age, body fluid mixtures and other factors on the properties of blood 

and bloodstain patterns produced from this blood. 
39

12. Research to improve methods for presenting bloodstain pattern evidence within the legal 

environment

Bloodstain pattern evidence presented in the legal environment is not always clearly 

communicated or understood. Research is required to develop new methods to clearly present 

this type of evidence. This could include the use of visual aids to illustrate evidence, statistical 

techniques for the expression of likelihood and novel communication techniques.