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

Department of Justice to prepare the following resource:

Document Title: A Multidisciplinary Validation Study of 

Nonhuman Animal Models for Forensic 

Decomposition Research

Author(s): Dawnie Wolfe Steadman, Ph.D., D-ABFA

Document Number: 251553

Date Received: March 2018

Award Number: 2013-DN-BX-K037

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

Justice. This resource is being made publically available through the 

Office of Justice Programs’ National Criminal Justice Reference 

Service.

Opinions or points of view expressed are those of the author(s) and 

do not necessarily reflect the official position or policies of the U.S. 

Department of Justice.
Department of Justice, Office of Justice Programs

National Institute of Justice

Grant # 2013-DN-BX-K037

A Multidisciplinary Validation Study of Nonhuman Animal Models for 

Forensic Decomposition Research

Submitted by:

Dawnie Wolfe Steadman, Ph.D., D-ABFA

Director of the Forensic Anthropology Center

Professor of Anthropology

865-974-0909; osteo@utk.edu

DUNS: 00-388-7891

EIN: 62-6--1636 

The University of Tennessee 

1 Circle Park Drive

Knoxville, TN 37996-0003 

Recipient Account: #R011005404 

Final Report

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Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
2 

Purpose and Objectives of the Project

Over the past century of scientific inquiry into the process of decomposition, nearly every 

mammal (and other taxa) has been studied. The earliest published studies, dating to the mid-19th century, 

were ecological studies designed to look at insect succession and development rates or insect behavior. 

For such studies, the type of carrion used was relatively inconsequential and depended upon what animals 

were locally available of the desired size. Some of the resulting theories and techniques of these 

approaches have been applied to forensic science. For instance, ecological entomology studies conducted 

on a wide range of carrion species has provided a basic scientific framework of insect succession and 

development that is the foundation of forensic entomology. Similarly, the morphological stages of 

decomposition were first described from observations of dogs (Reed 1958), pigs (Payne 1965) and guinea 

pigs (Bornemissza 1957). A potential problem may arise, however, when data derived from animal 

studies are applied to explain decomposition phenomena in forensic casework of human remains, 

particularly the postmortem interval. 

Our research informs an ongoing important debate about the applicability of nonhuman animal 

models in forensic research and its probative value in casework. Some argue that pigs are appropriate 

proxies for human subjects based on size, hair coverage and arthropod succession (e.g., Schoenly et al. 

2007). Our project determines if nonhuman animals exhibit the same forensically important 

characteristics as humans, such as arthropod succession, scavenging behavior, and morphological changes 

if external environmental factors are held constant. 

To date, attempts to address this question has been few and small-scale. Schoenly and colleagues 

(2007) placed two pigs and one human at the Anthropology Research Facility in Tennessee for 35 days. 

They found limited differences in anthropod preference between species and concluded that they 

“confirmed the claim that pig carcasses (of 23–27-kg starting mass) can substitute for human corpses in 

research and training programs, at least for summer-exposed and unconcealed remains in the first 5 wk 

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necessarily reflect the official position or policies of the U.S. Department of Justice.
3 

postmortem (2007:881).” Their oft-cited study to justify pig data as proxies for humans lacked replicates 

and covered only one season. Our research design is a comparative study of decomposition of 45 pig, 

rabbit and human subjects to assess if overall decomposition patterns and rates differ between carrion 

species and quantify any differences in scavenger and insect abundance, diversity and behavior across 

three seasons. 

The specific objectives of this project were to:

1) Apply the Total Body Scoring (TBS) system to make quantitative morphological comparisons 

between species during decomposition. The TBS system incorporates temperature and time such 

that individuals and species can be compared on the same scale. 

2) Assess insect taxonomic diversity and density differences among individuals and species. 

3) Evaluate if scavenger species and behavior differs among subject species and individuals. 

Project Design

The project was conducted at the Anthropology Research Facility at the University of Tennessee, 

Knoxville. This project compares five human, five domestic pig (Sus scrofa), and five domestic rabbit 

(Oryctolagus cuniculus) subjects in each of three seasonal trials. Human subjects were enrolled in the 

study if the weights were under 250 pounds and the bodies were not autopsied or otherwise exhibited

external trauma. Pigs and rabbits were supplied by local farms and were euthanized by a veterinarian. 

Target animal weights were between 100 and 150 pounds for pigs and over six pounds for rabbits (see 

Appendix 1). The protocols for animal handling and euthanasia were approved by the University of 

Tennessee Institutional Animal Care and Use Committee (IACUC) Protocol Form. All subjects were 

placed in a 38oF morgue cooler for at least 24 hours before placement to equalize body temperature. 

The trials occurred during three different seasons (spring, summer and winter) and 

microenvironments within the ARF. The 15 subjects in each trial were placed in transects within the 

same microenvironment within the ARF following a randomized block design (Appendix 2). The 

subjects were placed a minimum of three meters apart. Temperature and humidity data loggers were 

placed evenly along the transect to collect immediately local climatic conditions and six game cameras 

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4 

were established in the area to capture scavenger activity. Rabbits were placed in wire cages to prevent 

scavengers from removing them from the study area as one of our specific objectives was to examine 

insect activity variation by species. 

Climatological information was obtained from core body temperature, ambient temperature and 

humidity adjacent to the subjects, and daily mean temperatures from a nearby weather station. Core body 

temperatures were collected hourly via a rectal probe and data logger, though ultimately these data were 

not useful due to rapid equilibrium with ambient temperature. Site-specific ambient temperature and 

humidity were collected one meter above ground level adjacent to the subjects using 

temperature/humidity data loggers. Daily temperature, rainfall and humidity data were collected from the 

University of Tennessee Agricultural Campus Weather Station located approximately 0.5 miles from the 

ARF. All temperature data were converted to Accumulated Degree Hours (ADH) to follow standard 

practice in entomology (Byrd and Castner 2010) and anthropology (Simmons et al. 2010b). Only 

temperatures above 0oC were included in ADD calculations (Vass 2011, Megyesi et al. 2005). 

The progression of decomposition and photographic documentation was recorded twice daily 

(AM and PM) for each subject. The Total Body System (TBS) scoring method, which evaluates tissue 

coloration, bloating and loss on each body segment independently, was recorded following Megyesi et al. 

(2005) (see Appendix 3 for the scoring system and data collection form). 

Documentation of insect activity was recorded at each observation event. This includes adult 

insect arrival, presence of fly eggs and immature insects, fly larval migration and emergence of adult 

flies. Adult flies were collected using aerial sweep nets and then preserved in 70% ethanol. Fly larvae 

were collected using forceps and then placed in KAA. Other arthropods, including beetles, were 

preserved in 70% ethanol. Preservation methods from Catts and Haskell (1990) were followed. Adult and 

larval flies were classified to genera at minimum, and species level where possible. All identifications are

made using standard taxonomic keys and under the guidance of an entomologist (Amendt et al., 2011). 

The results of the taxonomic study will be forthcoming. 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
5 

To determine whether scavenger activity differs among the pigs and humans, six infrared, motion 

sensing Moultrie GAMESPY i60 digital game cameras were strategically placed across each transect to 

detect motion by a scavenger until the late stages of decomposition. The cameras were moved as physical 

signs of scavenging were noted during the daily observations. 

The relationship between TBS and PMI for each species were calculated in two ways. First, 

ADD was calculated from TBS using the formula, ADD = 10(0.002*TBS*TBS+1.81) ± 388.16 (Megyesi et al. 

2005). This was then plotted against the actual (“real”) ADD determined from the average daily high and 

low temperatures that were added together for the course of the trial. Second, a fuzzy clustering 

technique was applied to compare decomposition rates across the species. This technique is similar 

conceptually to discriminant analysis in that it helps to analyze group membership. It is unique in that it 

allows for the possibility of an observation belonging to more than one group. The variables were TBS 

and actual ADD. This technique was selected so that data from all three trials could be analyzed 

simultaneously, even though it represents 45 distinct individuals. The clustering analyses were conducted 

using NCSS 2007 statistical software. The technique allows the researcher to select how much overlap or 

how discrete the groups should be kept. For these analyses, groups were allowed to overlap, and 

observations could have equal probability of belonging to more than one group. 

Results

The chart in Appendix 4 demonstrates that the three trials did capture seasonality. Trial 1 took 

place in the spring and began prior to insect activity, while Trial 2 began and ended (quickly) during peak 

insect activity in June. Trial 3 was in the winter and, while the average temperature is 00C, many days 

dipped below 00C, including several snowfalls. Data were taken for each trial until 2000 ADH was 

reached, which in Trial 2 took only 16 days, though photos and insect samples were collected until day 45 

when most subjects had skeletonized (400 ADD). 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
6 

Decomposition Trends Between Species

The first step of our analysis examined whether the ADD estimated from the Total Body Scoring 

(TBS) system accurately tracks the real ADD based on the known time of placement of the body. The 

mean ADD estimated by the Megyesi TBS score was compared to the known ADD beginning with the 

date of placement at the ARF. The trends for each species were observed by averaging the estimated TBS 

scores for each individual for each day of the trial and then smoothed. 

None of the estimated ADD of any species had a strong correlation with real ADD in Trial 1, but 

the patterns between the species are also distinct (Appendix 5). The rabbits had an early decomposition 

rate that was much faster than that of either the pigs or humans. The pigs and humans tracked together 

well until insect activity began in earnest about 25 days into the trial and the pigs began to skeletonize 

faster than the humans. The human subjects had already mummified such that when insect activity did 

begin the flies were largely uninterested in non-fresh tissues and large maggot masses did not form. The 

pigs did not mummify, exhibited body-encompassing maggot masses, and therefore skeletonized more 

rapidly. This trend is best represented by the lower graph in Appendix 5. The estimated ADD of the 

humans largely underestimated the real ADD while the opposite is true for the rabbits early and most of 

the pigs later in decomposition. 

Trial 2 was in the summer and the graph in Appendix 6 illustrates that pig decomposition 

occurred more rapidly than that of the rabbits and humans. Insect oviposition was immediate and the pigs 

skeletonized faster than the other species. While the human remains were affected by insects, the 

progression towards skeletonization was slower than in the pigs and the soft tissue of the humans often 

mummified. 

A much different pattern emerged in Trial 3 (Appendix 7). Human decomposition occurred at a 

much faster rate than that of the nonhuman species. Moreover, one human subject in particular 

skeletonized more quickly than any of the other subjects. Trial 3 began on December 1 and no insect 

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necessarily reflect the official position or policies of the U.S. Department of Justice.
7 

activity occurred for over 100 days so the faster human decomposition rate is due solely to scavenging

(see below). 

The results from fuzzy clustering analysis offer more fine-grained insight into these general 

trends. In order to have a finer scale for the analyses, the data were broken into subsets: ADD less than 

100, 100-300 ADD and 300-400 ADD. 400 ADD was used as the cutoff because the second trial ended at 

400 ADD. 

The best solution for the early decomposition rates (under 100 ADD) was a two cluster option 

(Appendix 8). The pigs and humans made up the majority of the first cluster, with the second cluster 

being composed mainly of rabbits. The best solution was identified by three goodness of fit statistics; an 

average silhouette, Dunn’s coefficient, and Dc(U). The first two statistics are maximized, while the third 

is minimized when the solution is consistent. For 100-300 ADD, the best solution was again two clusters 

(Appendix 9). Similar to the previous analysis, the pigs and humans showed much more similarity than 

either group to the rabbits. This pattern is also true for ADD 300-400 (Appendix 10) in that pigs and 

humans remain more similar to each other throughout the decomposition process than either species does 

to the rabbits. 

Separating the data into each trial begins to show the seasonal variation more clearly, and the 

separation between species as well. Pigs and humans demonstrate a much more similar pattern to each 

other than to rabbits in Trial 1 between 100 and 300 ADD. This can be clearly seen when looking at 

photographs from this period; both pigs and humans display obvious color changes while the rabbit shows 

no outward indicator of decomposition progress (Appendix 11). Examining Trial 2 between 300 and 400 

ADD, a separation between all three species is observed. Morphologically, the humans had more visible 

mummification while the pigs showed higher amounts of bone exposure, and the rabbits showed changes 

that did not neatly correspond to any of the TBS categories (Appendix 12). Trial 3 showed a considerable 

amount of variability between the three species. The rabbits progressed very slowly, while the pigs 

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8 

demonstrated only minimal discoloration and desiccation. The humans had a significant amount of 

intraspecific variation due to scavenging (Appendix 13). 

Differential Insect and Scavenging Activity

Within each trial, the reason for the distinction between pigs and humans varied. For example, in 

Trial 2, the insect activity was more localized on the human subjects, while the entire body of the pigs 

were covered in larvae (Appendix 14). In contrast, species differences in Trial 3 was due to differential 

scavenging activity. 

Maggot activity occurred more rapidly and consumed the pigs and rabbits more completely than 

the humans. Notably, observing decomposition in rabbits in the same manner as humans is extremely 

difficult as changes cannot be visualized so the TBS scores may be misleading for the rabbits in the first 

and second trials. For instance, Appendix 15 shows Rabbit 4 four days after placement in Trial 2 and 

demonstrates significant maggot activity in the lower half of the body and skeletal elements are visible. 

However, less than 24 hours earlier this same rabbit showed no external signs of decomposition. There 

were no maggot masses on the face or anal region or anywhere externally observable until significant 

internal consumption had occurred. Thus, a systematic morphological observation system cannot be 

applied to rabbits. 

A total of four scavenger species were documented at the study areas but their activities varied by 

season and by subject species. Raccoons were the most commonly observed scavenger, followed by birds, 

opossum and skunk. Only human subjects were scavenged in Trials 1 and 2 (two humans in Trial 1 and 

four in Trial 2) and the overall impact of scavenging was relatively minimal given the amount of 

consumption by the insects. However, all five human subjects were scavenged in Trial 3, which occurred 

before significant scavenging of other species. Appendix 16 shows the number of days after placement in 

which scavenging is first observed on each scavenged subject. This indicates that all three species were 

initially scavenged with some additional human subjects added before most of the pigs. However, 

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9 

scavenging of the two earliest pigs were either the tongue pulled out (but not actually consumed) from 

one pig and a small penetration of the abdomen (nipple removal) on the other. The fur was also extracted 

from the rabbits early on (and raccoons could have easily accessed the remains in the cage), yet this graph 

of the second date of scavenging demonstrates that the scavengers did not return to the pigs or any of the 

rabbits until after all five of the humans had been scavenged. This strongly indicates a preference for the 

humans over the other species. 

All of the humans and eventually all of the pigs were scavenged in Trial 3, but the timing and 

anatomical distribution of scavenging greatly differed. With one notable exception in which scavenging 

began on the face, human scavenging began on the limbs while the snout, abdomen, neck and back were 

the initial preferred scavenging sites on pigs given the anatomical distribution of muscle in the pig. In the 

future we will create heat maps of the scavenging distribution, timing and number of scavenging events 

for each species. 

The TBS method did not estimate accumulated degree days reliably for any of the species in any 

trial. The method does not take into account scavenging, which can result in rapid skeletonization in 

different regions of the body, nor differential decomposition within an anatomical region. Though the 

total body scores are supposed to be unidirectional and sequential, scavenging of the face may result in a 

score jumping from 1 (fresh) to 10 or 11 in a single day. Moreover, differential scavenging of the limbs is 

ignored by the TBS because only the lower score is used. Improvement of the total body score method 

should include a separate category for scavenging and a larger number of body regions. 

Implications for Criminal Justice Policy and Practice in the U.S.

The results of this study clearly demonstrate differential decomposition among humans and 

nonhuman animals. Rabbits do not make a suitable proxy for humans; they are consistently different in 

their decomposition rates and patterns and do not permit the application of any morphological scoring 

system that can be applied to humans. Pig decomposition is closer to humans but still differ in overall 

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Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
10

decomposition trends. Namely, pigs show less intraspecific variation (perhaps due to same diet, weight, 

age, etc). This means that pigs could be useful for certain baseline decomposition data (e.g., determining 

what carrion insects are present in a certain environment) but lack important variability seen in the human 

decomposition patterns. In particular, the intensity and pattern of scavenging observed on the human 

subjects is not captured by the nonhuman study subjects while insect activity may not be as impactful for

humans as it is for pigs. Seasonality also plays a role in differential decomposition as pigs and rabbits 

decompose faster than humans when insects are present and scavenging is more likely to occur in the 

winter. In sum, our data indicates that human data is best for determining human patterns of 

decomposition in forensic cases. 

Scholarly Products

Conference Papers Presented:

2016 Steadman DW, Dautartas AM, Jantz LM, Mundorff AZ, Vidoli GM. A Multidisciplinary 

Validation Study of Nonhuman Animal Models for Human Decomposition Research. 

Paper presented at the National Institute of Justice Forensic Science Research and 

Development Symposium, Las Vegas, NV. February 23, 2016. 

2016 Steadman DW, Dautartas AM, Mundorff AZ, Vidoli GM, Jantz LM. Differential 

Raccoon Scavenging Among Pig, Rabbit, and Human Subjects. Paper presented at the 

American Academy of Forensic Sciences, Las Vegas, NV. February 27, 2016. 

2016 Dautartas AM, Steadman DW, Mundorff AZ, Jantz LM, Vidoli GM. A Comparison of 

Seasonal Decomposition Patterns Between Human and Nonhuman Animal Models. Paper 

presented at the American Academy of Forensic Sciences, Las Vegas, NV. February 26, 

2016. 

2015 Dautartas AM, Jantz LM, Vidoli GM, Steadman DW. A Multidisciplinary Validation 

Study of Nonhuman Animal Models for Forensic Decomposition Research: A Time 

Series Approach. Paper presented at the American Academy of Forensic Sciences, 

Orlando, Florida. February 19, 2015. 

 

Publications in Preparation: 

Dautartas AM, Jantz LM, Vidoli GM, Steadman DW. Differential insect activity and taxonomy across 

human and nonhuman subjects. A Comparison of insect activity and taxonomy between humans and 

nonhuman animal models across three seasons. Paper to be submitted to Forensic Science International. 

Steadman DW, Dautartas AM, Mundorff AZ, Vidoli GM, Jantz LM. Differential Raccoon Scavenging 

Among Pig, Rabbit, and Human Subjects. Paper to be submitted to the Journal of Forensic Sciences. 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
11

Dautartas AM, Steadman DW, Mundorff AZ, Jantz LM, Vidoli GM. A Comparison of Seasonal 

Decomposition Patterns between Human and Nonhuman Animal Models using Fuzzy Clustering. Paper 

to be submitted to the Journal of Forensic Sciences. 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
12

Appendices

Appendix 1. Weight and sex data for human subjects and weight data for pig and human 

subjects in all three trials.

Subject Trial 1 Sex/Weight Trial 2 Sex/Weight Trial 3 Sex/Weight

Human 1 Male/179 Female/123 Female/126

Human 2 Female/159 Male/147 Female/173

Human 3 Male/186 Female/116 Male/188

Human 4 Male/167 Male/191 Female/186

Human 5 Male/167 Female/235 Male/161

Pig 1 140 113 103

Pig 2 133 104 106

Pig 3 140 106 126

Pig 4 148 130 117

Pig 5 150 88 106

Rabbit 1 8 9 7

Rabbit 2 8 8 8

Rabbit 3 6 7 5

Rabbit 4 7 8 7

Rabbit 5 8 8 9

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13

Appendix 2. Photograph of the transect of subject placement in Trial 1. 

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14

Appendix 3. Total Body Score data collection form and TBS scoring categories. 

Recorder: 

Date: 

Megyesi scoring data collection sheet

Human: 

Donation Head & Neck Trunk Limbs TBS Est. ADD Comments

AM PM AM PM AM PM

Pig: 

Individual Head & Neck Trunk Limbs TBS Est. ADD Comments

AM PM AM PM AM PM

1

2

3

4

5

Rabbit: 

Individual Head & Neck Trunk Limbs TBS Est. ADD Comments

AM PM AM PM AM PM

1

2

3

4

5

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15

Categories and stages of decomposition for the head and neck.

Categories for the Trunk

Limbs

 

A. Fresh

1. Fresh, no discoloration. 1 pt

B. Early Decomposition

1. Pink-White appearance with skin slippage and some hair loss. 2 pts

2. Gray to green discoloration: some flesh still relatively fresh. 3 pts

3. Discoloration and /or brownish shades particularly at edges, drying of nose, ears, and lips. 4 pts

4. Purging of decompositional fluids out of eyes, ears, nose, mouth, some bloating of neck and face may be present. 5 pts

5. Brown to black discoloration of flesh. 6 pts

C. Advanced decomposition

1. Caving in of the flesh and tissues of eyes and throat. 7 pts

2. Moist decomposition with bone exposure less than one half that of the area being scored. 8 pts

3. Mummification with bone exposure less than one half that of the area being scored. 9 pts

D. Skeletonization

1. Bone exposure of more than half of the area being scored with greasy substances and decomposed tissue. 10 pts

2. Bone exposure of more than half of the area being scored with dessicated or mummified tissue. 11 pts

3. Bones largely dry, but retaining some grease. 12 pts

4. Dry bone. 13 pts

A. Fresh

1. Fresh, no discoloration. 1 pt

B. Early Decomposition

1. Pink-white appearance with skin slippage and marbling present. 2 pts

2. Gray to green discoloration: some flesh still relatively fresh. 3 pts

3. Bloating with green discoloration and purging of decompositional fluids. 4 pts

4. Postbloating following release of the abdominal gases, with discoloration changing from green to black. 5 pts

C. Advanced Decomposition

1. Decomposition of tissue producing sagging of flesh; caving in of the abdominal cavity 6 pts

2. Moist decomposition with bone exposure less than one half that of the area being scored. 7 pts

3. Mummification with bone exposure less than one half that of the area being scored. 8 pts

Skeletonization

1. Bones with decomposed tissue, sometimes with body fluids and grease still present. 9 pts

2. Bones with dessicated or mummified tissue covering less than one half of the area being scored. 10 pts

3. Bones largely dry, but retaining some grease. 11 pts

4. Dry bone. 12 pts

A. Fresh

1. Fresh, no discoloration. 1 pt

B. Early Decomposition

1. Pink-white appearance with skin slippage on hands and/or feet. 2 pts

2. Gray to green discoloration: marbling; some flesh still relatively fresh. 3 pts

3. Discoloration and/or brownish shades, particularly at edges, drying of fingers, toes, and other extremities. 4 pts

4. Brown to black discoloration, skin having a leathery appearance. 5 pts

C. Advanced Decomposition

1. Moist decomposition with bone exposure less than one half that of the area being scored. 6 pts

2. Mummification with bone exposure less than one half that of the area being scored. 7 pts

D. Skeletonization

1. Bones exposure over one half of the area being scored, some decomposed tissue and body fluids remaining. 8 pts

2. Bones largely dry, but retaining some grease. 9 pts

3. Dry bone. 10 pts

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16

Appendix 4. Season, dates, temperatures and duration of Trials 1-3.

Trial Season Placement Date Max Low 

(0C)

Max High 

(0C)

Avg 

Temp 

(0C)

Study 

Duration

1 Spring March 14, 2014 2.6 24.2 16.2 75 days

2 Summer June 13, 2014 19.5 28.7 24.2 45 days

3 Winter December 1, 

2014

0 17.8 5.1 123 days

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17

Appendix 5. Plots of estimated ADD calculated by TBS scores and known ADD by species 

(top) and data by individual (bottom) for Trial 1 (spring). The rabbit decomposition rate is 

initially faster than the other species but pig decomposition accelerated when insect activity 

began. Human decomposition slowed despite insect availability due to mummification.

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18

Appendix 6. Plots of estimated ADD calculated by TBS scores and known ADD by species 

(top) and data by individual (bottom) for Trial 2 (summer). Pig decomposition was more rapid 

due to rapid and intense insect activity. 

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19

Appendix 7. Plots of estimated ADD calculated by TBS scores and known ADD by species 

(top) and data by individual (bottom) for Trial 3 (winter). Human decomposition was much 

faster due to scavenging. The scavengers preferred humans overall but especially one subject. 

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20

Appendix 8. Fuzzy clustering analysis of known ADD and TBS score for all species across all 

trials for the first 100 ADD. The ellipses represent 95% of the variation. There are clear outliers 

from all three species. The pigs and humans cluster together in the first cluster and rabbits form 

the majority of the second cluster. Average silhouette: .4, Dunn’s coefficient: .58, Dc(U): .42.

TBS vs ADD by species

ADD

-20 20 60 100 140 -2

3

8

13

18

Variables

human

pig

rabbit

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21

TBS vs ADD by species

ADD

50 100 150 200 250 300 350 -10

5

20

35

Variables

human

pig

rabbit

Appendix 9. Fuzzy clustering analysis of known ADD and TBS score for all species across all 

trials between 100 and 300 ADD with all data points (top) and without (bottom). Average 

silhouette: .95, Dunn’s coefficient: .98, Dc(U): .01. 

TBS vs ADD by species

ADD

50 100 150 200 250 300 350 -10

5

20

35

Variables

human

pig

rabbit

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
22

Appendix 10. Fuzzy clustering analysis of known ADD and TBS score for all species across all 

trials between 300 and 400 ADD with all data points (top) and without (bottom). Average 

silouhette: .57, Dunn’s coefficient: .79, Dc(U): .21. 

TBS vs ADD by species

ADD

260 290 320 350 380 410 440 -10

5

20

35

Variables

human

pig

rabbit

TBS vs ADD by species

ADD

260 290 320 350 380 410 440

-10

5

20

35

Variables

human

pig

rabbit

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
23

TBS vs ADD by species

ADD

0 100 200 300 400 -6

-2

2

6

10

14

18

Variables

human2

pig2

rabbit2

Appendix 11. Fuzzy cluster of all three species in Trial 1 between 100 and 300 AD 

demonstrating tighter clustering of the humans and pigs. The pigs and humans demonstrate 

color changes, though none are observable on the rabbits (bottom). 

 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
24

TBS vs ADD by species

ADD

150 300 450 600 16

19

22

25

28

31

34

Variables

human

pig

rabbit

Appendix 12. Fuzzy cluster of all three species in Trial 2 between 300 and 400 AD shows 

differentiation of decomposition rates among the species and complete separation of the rabbit 

pattern from the pig and humans. Note skeletonization of the pig due to insect activity but 

mummification of the human.

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
25

TBS vs ADD by species

ADD

260 300 340 380 420 5

15

25

35

45

Variables

human2

pig2

rabbit2

Appendix 13. Fuzzy cluster of all three species in Trial 3 between 300 and 400 AD shows much 

higher TBS scores for humans due to scavenging. Note nearly complete skeletonization of the 

human subject while the pig and rabbit are still in the fresh stage (below). 

 

 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
26

Appendix 14. Differential insect activity on the human on Day 7 of Trial 2 in which maggot 

activity is localized (top) and pig (bottom) on Day 6 of the same trial. 

 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
27

Appendix 15. Rabbit 4 in Trial 2 demonstrating maggot activity and skeletonization of the lower 

limbs four days after placement (top). However, there is no evidence of insect activity 24 hours 

earlier, indicating that insect activity and overall morphological changes during decomposition is 

more difficult to observe in rabbits due to fur. 

Rabbit 4 on June 17 am

Rabbit 4 on June 16 am

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
28

Appendix 16. Time of first (top) and second (bottom) scavenging on the 15 subjects in Trial 3. 

While scavengers visited some pit and rabbit cadavers early, they did not return to the bodies 

until all of the human subjects had been scavenged. 

 

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6

PMI

Individual

Day of First Scavenging

Human

Pig

Rabbit

0

20

40

60

80

100

120

0 1 2 3 4 5 6

PMI

Individual

Second Scavenging Event

Human

Pig

Rabbit

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.
29

Appendix 17. References 

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applications and limitations. Forensic Sci Med Pathol 7:379–392. 

Bornemissza GF. 1957. An analysis of arthropod succession in carrion and the effect of its 

decomposition of the soil fauna. Australian Journal of Zoology 5:1-12. 

Byrd, J, and J. Castner. 2010. Forensic Entomology: The Utility of Arthropods in Legal 

Investigations, 2nd Edition. CRC Press, Inc., Boca Raton, FL. 

Catts EP, Haskell NH, editors. 1990. Entomology & death: a procedural guide. Forensic 

Entomology Assocs.

Megyesi MS, Nawrocki SP, Haskell NH. 2005. Using accumulated degree days to estimate the 

postmortem interval from decomposed human remains. Journal of Forensic Sciences 50(3):618–

26. 

Payne JA. 1965. A summer carrion study of the baby pig Sus scrofa. Ecology 46:592-602. 

Reed J. 1958. A study of dog carcass communities in Tennessee, with special reference to the 

insects. American Midland Nature 59:213-245. 

Schoenly KG, Haskell NH, Hall RD, Gbur JR. 2007. Comparative performance and 

complementarity of four sampling methods and arthropod preference tests from human and 

porcine remains at the Forensic Anthropology Center in Knoxville, Tennessee. Journal of 

Medical Entomology 44:881-894. 

Simmons T, Cross T, Adlam RE, Moffat C. 2010b. The influence of insects on decomposition 

rates in buried and surface remains. Journal of Forensic Sciences 55(4):889-892. 

Vass AA. 2011. The elusive universal postmortem interval formula. Forensic Science 

International 204(1-3):34-40. 

This resource was prepared by the author(s) using Federal funds provided by the U.S. 

Department of Justice. Opinions or points of view expressed are those of the author(s) and do not 

necessarily reflect the official position or policies of the U.S. Department of Justice.