Project SummaryThe aim of this proposal is to better estimate the time of death for homicide victims with stab wounds that have passed the time frame for an estimated post mortem interval (PMI). The quantification of rate of decomposition for victims of stab wounds is a subject that is lacking within the forensics field. The use of domestic pig as a human model within a control and stab group for each season of the calendar year will be monitored for the rate of decomposition. Each carcass will be weighed to measure mass loss throughout the decomposition process. After each carcass has reached the remains stage, statistical analysis will be used to compare weights and rates of each group. Through this research, a more accurate timing of death can be established for homicide victims with stab wounds.

Introduction• Environmental variables including temperature, rainfall,

and injuries can affect the rate of decomposition (Goff 2009)

• Domestic pig is a commonly used model for human decomposition experiments due to similar fat, muscle, and hair ratio (Goff 2009)

• Cross and Simmons (2010) showed that penetrative trauma (bullet wounds) does increase the rate of decomposition. Seasons were also compared showing that summer had the fastest rate of decomposition while winter had that slowest. Pig carcasses were weighed and it was determined that disturbance of carcasses slowed the rate of decomposition.

• Goff (2009) discussed common events that can occur in different environments such as the formation of adipocere and skin slippage. Goff also described the 5 common stages of decomposition (fresh, bloated, decay, post decay, and remains) as well as the different types of insects that are likely to appear during each stage.

Objectives• Examine and quantify how stab wounds and seasonal changes

affect the onset and duration of the 5 stages of decomposition

• Measure weight loss to track differences in pattern and timing for each season and experimental group.

Review of Literature• The five stages of decomposition consist of the fresh, bloated,

decay, post decay, and remains. (Goff 2009)• Many variable can affect the rate of decomposition (Goff 2009

Cross and Simmons 2010)• Increased temperature increases the rate of decomposition, lower

temperatures slow decomposition and also change the pattern of decomposition (Goff 2009 Cross and Simmons 2010).

• Penetrative trauma (bullet wounds) increased the rate of decomposition and had higher mass loss than control (Cross and Simmons, 2010).

• Domestic pig is used in forensic experimentation due to similar ratio of fat, hair, and skin to that of humans (Goff 2009 Cross and Simmons 2010).

Acknowledgements• I’d like to thank Dr. Rehnberg of the biology department and Dr. Hanburry from the Criminal Justice Department for help in

conducting research and the design of the materials and methods section of my manuscript.

Literature cited• Cross, P. and Simmons, T. 2010. The Influence of Penetrative Trauma on the Rate of Decomposition. Journal of

Forensic Sciences 55: 295-301.• Goff, M. Lee. 2009. Early post-mortem changes and stages of decomposition in exposed cadavers. Experiment

and Applied Archeology 49:21-36.• http://reflexions.ulg.ac.be/upload/docs/image/png/2012-08/pig-decay-stages.png

Research Design

Methods:• Pigs will be killed by captive bolt pistol and wound sealed with

pithing cane and plasticine (Cross and Simmons 2010).• Stabbed pigs will be stabbed with a Kitchenaide Ceramic Chef Knife

of 15.24 cm.• Each seasons’ placement day will be the first day of that season

and will be weighed using an American Weigh Scale-t1440 Industrial Heavy Duty Digital Hanging Scale

• With each stage of decomposition identified, weight will be measured and day will be noted.

Bridgett Dougherty, Department of Biology, York College

The Effects of Stab Wounds on Body Mass Loss and Duration of Decomposition in Pigs

Figure 2. Schematics of weighing apparatus to be used to weigh individual pigs.

http://reflexions.ulg.ac.be/upload/docs/image/png/2012-08/pig-decay-stages.png

0 25 50 75 1000

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Figure 4. Expected body mass loss for the seasons of(A) winter, (B) spring, (C) summer, (D) fall.

Table 1. Overview of decomposition stage duration (days) from literature using pig carcasses.

Author Environment Stage One Stage Two Stage Three

Stage Four Stage Five

Anderson and Hobischak (2004)

Coast (land) 0 2 11 17 43 Fresh Running

0 9 42 105 280

Fresh Stagnant

0 9 42 105 280

Archer1

(2003) Summer 0 1-7 12.6 19.6 30.8 Autumn 0 1-7 39.2 58.8 85.4 Winter 0 14 42 91 98 Spring 0 1-7 18.2 25.2 65.8

1 Mean data modified from Archer (2003)

Expected Results

Hypothesis:• Presence of stab wounds will increase rate of decomposition

and quicker mass loss

• Colder temperatures will decrease rate of decomposition and slow mass loss

Number of pigs

Control Stabbed

Winter Summer FallSpring

Project SummaryThe aim of this proposal is to aim in the determination of time of death for homicide victims with stab wounds that have passed the time frame for an estimated post mortem interval (PMI). The quantification of the rate of decomposition for victims of stab wounds is a subject that is lacking within the forensics field. The use of domestic pig as a human model within a control and stab group for each season of the calendar year will be monitored for the rate of decomposition. Each carcass will be weighed to measure mass loss throughout the decomposition process. After each carcass has reached the remains stage, statistical analysis will be used to compare weights and rates of each group. Through my research, a more accurate timing of death can be established for homicide victims with stab wounds.

Introduction• Environmental variables including temperature,

rainfall, and injuries can affect the rate of decomposition (Goff 2009)

• Domestic pig is a commonly used model for human decomposition experiments due to similar fat, muscle, and hair ratio (Goff 2009)

• Cross and Simmons (2010) showed that penetrative trauma (bullet wounds) does increase the rate pf decomposition. Seasons were also compared showing that summer had the fastest rate of decomposition while winter had that slowest. Pig carcasses were weighed and it was determined that disturbance of carcasses slowed the rate of decomposition.

• Goff (2009) discussed common events that can occur in different environments such as the formation of adipocere and skin slippage. Goff also described the 5 common stages of decomposition (fresh, bloated, decay, post decay, and remains) as well as the different types of insects that are likely to appear

during each stage.

Objectives• Examine and quantify how stab wounds and seasonal

changes affect the onset and duration of the 5 stages of decomposition

• Measure weight loss to track differences in pattern and timing for each season and experimental group.