4. Post-Mortem Investigation
Coroners9
› Designated public official
› Not required to be medical
doctors
› Determines cause and manner of
death
› Can employ specialists to
preform autopsies for
questionable death
Medical Examiner9
› Hired medical doctors
› Must have some kind of medical
degree
› Determines cause and manner of
death
› Encouraged to take classes to
specialize or further their
education if not already
specialized
5. Post-Mortem Investigation
› An Autopsy is the examination of a body in order to determine
a cause of death in unknown cases or to study a death in the
case of disease. 4
› They provide:
– Possible evidence for police investigation
– Time of Death
– Cause of Death
6. Time of Death
› Post-mortem Interval (PMI)
› Why is it important to understand time of death, or PMI?
– Recreating crime scenes
– Retracing the victims last 48 hours
Helps determine possible suspects and can aid in
understanding cause of death6
9. Post-Mortem Interval5
› How is time of death currently determined?
– Stage of decomposition
– Contents of digestive tract
– Shape and fluidity of eyes
– Skin slippage
– Conditions of trauma
– Insect activity
10. Stages of Decomposition2
1. Fresh- autolysis
– Algor mortis: changes in temperature
– Liver mortis: changes in circulation, “lividity”
– Rigor Mortis: muscle stiffness due to lack of ATP
2. Bloat- Putrefying causes chemical breakdown, releasing gases
primarily in the abdomen
3. Active Decay- main internal decomposition; protein,
carbohydrate, and fat degradation
4. Advanced Decay- further breakdown of cartilage and skin
5. Skeletonisation- only bones and hair remain
11. Other Methods1
› DNA degradation-looking at the presence/ complexity of DNA
present in bodily fluids after death to determine time of death
– Not yet reliable due to too many variables, both externally and
internally. Also too heavily effected by small human error.
› RNA degradation-looking at the presence/ complexity of RNA
present in bodily fluids after death to determine time of death
– Has been successfully studied in rats but has not yet been studied in
humans due to the difficulty in acquiring enough bodies to study
12. Thesis
By improving technology and understanding the process of
post-mortem degradation, proteins and other volatile organic
compounds can be used to more accurately determine a post-
mortem interval
13. Mass Spectroscopy
› Uses mass to charge ratio to identify molecules
› Ways to collect mass spec
– Gas Chromatography
– Electrospray Ionization (ESI)
– Desorption Electrospray Ionization (DESI)
– Solid-phase Microextraction (SPME)
14. Protein Analysis
› As the body degrades proteins are released in various
concentrations over time
› Many different products, volatile organic compounds (VOC)
are released as either a gas or a liquid due to protein
degradation and the lack of metabolism
15. Studies
› A study conducted in Belgium used decaying pig carcasses in 3
different environments 2
› Samples were analyzed using coupled GC-MS
– Over 104 compounds were found during different stages of
decomposition
– Followed the degradation of four different biological molecule
categories
› Proteins
› Nucleic acids
› Lipids
› Carbohydrates
17. VOC formation7
› Triglycerides Glycerol and fatty acids
› Glycerol Pyruvate lactic acid, formic acid, acetic acid, 1-
butanol
› Many other chemicals are released by every aspect of the
human body!
21. How to detect VOCs
› Using the previous techniques, samples were successfully
analyzed using mass spec
› Portable gas or liquid collection
– Allow crime techs or medical examiners to collect samples on site and
analyze back in lab
– Cuts down on crime scene contamination
22. Where to now?
› Technology
– Using current mass spec and chemistry analysis techniques,
specifically DESI, develop portable and easy to use technology that
can be operated by medical examiners and field crime technicians
› Master list
– Using mass spec and understanding of the external affects on
decomposition a list can be created comparing the average
concentration of VOCs released to hours since death.
23. Research at Mount St. Mary’s
› Utilizing DESI, a database of post-mortem VOCs is being
complied including
– Mass Spec
– Time frame of degradation
› Once this is complete, technique of DESI sampling will be
applied to small scale “field” sampling
25. Sources
1. Chengzhi Li, Qi Wang, Yinming Zhang, Hancheng Lin, Ji Zhang, Ping Huang & Zhenyuan
Wang (2016)Research progress in the estimation of the postmortem interval by Chinese
forensic scholars, Forensic Sciences Research, 1:1, 3-13,
2. Dekeirsschieter, J., Verheggen, F.J., Gohy, M., Hubrecht, F., Bourguignon, L., Lognay, G.C., &
Haubruge, É. (2009). Cadaveric volatile organic compounds released by decaying pig carcasses
(Sus domesticus L.) in different biotopes. Forensic science international, 189 1-3, 46-53.
3. Diamond, Stephen A. “Who Killed JonBenet?” Psychology Today, Sussex Publishers, 18 Jan. 2017,
www.psychologytoday.com/us/blog/evil-deeds/201701/who-killed-jonbenet.
4. Gerbis, Nicholas. “What Exactly Do They Do During an Autopsy?” LiveScience, Purch, 26 Aug. 2010,
www.livescience.com/32789-forensic-pathologist-perform-autopsy-csi-effect.html.
5. “Homicide Investigations: How to Determine Time of Death.” Forensics Colleges, Sechel Ventures,
www.forensicscolleges.com/blog/resources/how-to-determine-time-of-death.
6. Lyle, D.P. “Time of Death: A Critical Part of the Timeline.” WritersDigest.com, F+W, 3 Apr. 2008,
www.writersdigest.com/qp7-migration-books/forensics-excerpt.
26. Sources cont.
7. Paczkowski, Sebastian, and Schütz Stefan. “Post-Mortem Volatiles of Vertebrate
Tissue.” Applied Microbiology and Biotechnology, vol. 91, no. 4, 2011, pp. 917–935.,
8. Stadler, S., Desaulniers, J., & Forbes, S. L. (2015). Inter-year repeatability study of volatile
organic compounds from surface decomposition of human analogues.International
Journal of Legal Medicine, 129(3), 641-650.
9. “So You Want To Be A Medical Detective .” Thename, NaME,
www.thename.org/assets/docs/2f8ae9c9-39b0-49d2-a10f-5980e0770526.pdf
10. Vass, Arpad A. "Beyond the Grave - Understanding Human Decomposition." Microbiology
Today 28.1 (2001): 190-192.
Editor's Notes
Forensics is where science and the law over lap. Using multiple different fields of science, data can be applied to aid in the investigation of any crime.
There are several applications of forensics under many different types of sciences
Ballistics (physics)
Toxicology (Chemistry)
Blood spatter (Physics)
Entomology (Biology)
Pathology (biology/medicine)
-cause of death is exactly that, what killed the person (blunt force trauma, poisoned, etc.)
-manner is how it happened. There are 4 manners of death; Homicide, Suicide, Natural causes, and accidental
-M.E’s are not required to specialize in pathology, but very commonly they are forensic pathologists or regular medical doctors that specialize in death investigation
-Expectation that M.E’s have a more sophisticated medical expertise than coroners
-People that do specialize in forensic pathology are expected to know beyond basic medical facts (know more about other basics of forensics, ballistics, toxicology, etc.)
-10 states use only coroners, 23 states use only medical examiners, and 18 states use both
https://www.thename.org/assets/docs/2f8ae9c9-39b0-49d2-a10f-5980e0770526.pdf
-evidence, like bullets or identifying/odd wounds which could indicate a weapon
Integral part of every investigation
Beauty Pageant queen from Colorado
She was born in 1990 and died Christmas of 1996
She was found murdered the morning after a Christmas party in the Ramsey’s home.
Even over 20 years after her murder investigators still have yet to find the perpetrator or even determine the day that she died. It is still unsure if she died on Dec. 25th or Dec. 26th.
The morning after a Christmas party, Patsy Ramsey noticed her daughter was missing. She went to go downstairs and found a ransom note on the stairs. She quickly called the police around 6 am and a full investigation was launched. It wasn’t until much later (around 1 pm) that the girls body was found. After figuring out how she died (asphyxiation from the garrote) it came to question who killed her? To figure that out investigators needed to know WHEN she died.
https://www.psychologytoday.com/us/blog/evil-deeds/201701/who-killed-jonbenet
The main suspects of the case were her mother Patsy, her father John, her brother Burke and a wild card suspect- Bill McRenyolds who had been at the party dressed as Santa Clause.
During the autopsy one of the important discoveries was the fruit in JonBenét’s stomach, it was determined to be pineapple and was only eaten a few hours before her death. Her parents claimed no one fed her pineapple, however the brother’s finger prints were found all over a bowl of pineapple that was in the kitchen.
If a time of death had been accurately determined it would provide insight to the timeline of her last hours and hopefully help identify her murderer based on who was in the home at the time of her death.
Last meal and how far it has been digested
Skin color and elasticity change
Is there any dried blood on the victim or crime scene? Are the wounds still fresh or are they decomposing already?
Age/development of insects, assuming eggs were laid relatively close to time of death or at least during the fresh stage.
Autolysis- body breaking down itself
Lividity- the pooling of blood depending on how the body is positioned. If a person is dead sitting up in a chair the blood will pool in the feet and behind/lower back.
Lack of ATP- oxygenate metabolism is impossible post mortem and no reactions are being energetically stimulated so the body no ATP is being produced. Also accounts for a build up of lactic acid.
Protein degradation is predominantly during Active decay due to the slow down and stopping of glycolysis
There is a group of scientists from China currently studying different molecular methods of determining post-mortem interval
However neither has been successful yet
Gas chromatography- the sample has to be able to be transformed into gas phase, the molecules are heated up and pushed through a coil at different speeds depending on the molecules size and can then be picked up by the mass spec
Electrospray ionization – samples are put under a spray solution that ionizes the sample and causes fragmentation of the molecule. The ion fragments are then analyzed by the mass spec
DESI- very similar to esi but allows for ambient sampling
SPME- samples are collected using a small fiber and then analyzed through gas chromatography
Pigs are found to be the best human analogues in post mortem research because they are biologically similar and much more readily available.
Dekeirsschieter et al
A similar study also used pig carcasses and looked at the effect of temperature on decomposition and found the relative abundance of different chemicals in comparison to days post mortem.
Stadler, S
List of chemicals collected and found in all three sites (forest, urban, and agricultural). The lists are all very generalized, listing specific chemicals but not acknowledging sampling site or when it was released post mortem.
(Dekeirsschieter et al.)
A different paper traced where each VOC came from with in the body and which process lead to its formation.
Triglycerides are broken down by microbial lipolytic enzymes
Glycerol and pyruvate are broken down by other bacteria in the body and external environment
Bone marrow and other proteins are broken down by bacteria and fungus while the minerals of bone are degraded by physical weathering
(Paczkowski et al.)
Studies have already determined where VOCs stem from with in the body
(Paczkowski et al.)
Temperature:
Drop in temperature can slow the process while high temperature’s will increase the process of degradation
Bacteria/fungus: Can aid in the digestion of certain proteins and increase the rate of degradation
Fly infestation or scavenging animals; missing parts, and increase rate of degradation
All of these things would have to be taken into account when looking at the levels of proteins and VOCs released in an actual crime scene, not just a controlled research environment
Previously conducted studies are using gas chromatography to create specialized devices to pick up on vocs. This first study created a hood that would be placed over the decaying carcass and gas would be pulled up into a sampling tube by an attached pump. The gas sample was then taken A second study used a modified hair dryer to create a sampling device using SPME that uses a vacuum to pull in air. In both of these studies the most appealing aspect is the portability of it all, this would allow medical examiners to take the device directly to the crime scene
