The Relation between Forensic Science and Chemistry
Isabelle Génier
London Central Secondary School

There is a great number of careers that involve chemistry; being a forensic scientist is one of them. What is a forensic scientist you ask? That is a very difficult question to answer. Generally they provide evidence in court to support the prosecution or defence in criminal and civil investigations. The evidence can be provided in the form of a written paper or the scientist might be called to testify during trials or hearings as an expert witness on evidence or laboratory techniques. There are different areas of forensic science such as chemistry (which involves crimes against property), biology (which involves crimes against people), and toxicology (which majorly involves drugs).
Being a forensic scientist involves many tasks, they go to crime scenes to investigate and then plan what evidence they need to collect. Afterwards they return to compile, catalogue, and preserve evidence to help solve the case. They then do a sketch of the scene so that they can later reconstruct the crime scene to re-examine, test, and analyze the evidence. Now that the evidence has been assessed, it can be discussed between specialists and a report can be written based on their conclusions. The report is used during trials or hearings; however, the forensic scientist can also be called upon to personally testify as an expert witness.
This career, which used to be an unknown field has now become a very trendy occupation thanks to the many popular investigative television series such as Bones, Castle, and Dexter. Some key forensic scientists that contributed to make this field so well-known are Mathieu Orfila and Bernard Spilsbury. Orfila was involved in the bringing of chemistry into forensic science by studying asphyxiation, decomposition of bodies, and exhumation (explained later in the paper). He discovered that a body buried in soil that has been tested to contain arsenic was not necessarily poisoned. This is because the body can absorb the arsenic that was found in the soil. This discovery made it so that during all exhumation cases, the soil must be tested.
Bernard Spilsbury’s work was very controversial but nonetheless he contributed to forensic science. One of his most famous cases is the death of Dr. Crippen’s wife, Cora. He tested the flesh found in Crippen’s cellar and discovered that it showed signs of scar tissue. Cora had a scar due to an operation she’d had, and so Spilsbury concluded that Dr. Crippen was the culprit. This is controversial since the scar tissue did not necessarily mean that it belonged to Cora. Another famous case of Spilsbury’s is the murder of Emilienne Gerard. By dissecting her stomach he identified what she’d eaten, and so was able to trace the food back to a Belgian butcher. Spilsbury then tested the blood in the butcher’s workplace to see if it belonged to an animal’s or to Emilienne. The sample was too small and so the results were inconclusive, however the butcher was still held responsible.
As mentioned earlier, the relation of asphyxiation, decomposition of bodies, and exhumation to forensic science will now be explained. Asphyxiation is when a person’s airway is blocked causing them to not get enough oxygen, ultimately causing their death (for example strangling someone is asphyxiation). Although there are many physical signs of asphyxiation, such as bruising on the neck and bloodshot eyes, there is also chemical evidence. During an autopsy, if there is a build-up of carbon dioxide waste in the deceased tissues then there is a chance the victim suffered from asphyxiation.
As for the decomposition of bodies, there has recently been a discovery in the area of forensic chemistry. Odours released from decomposing bodies can now be used as a tool to find out how long a corpse has been dead, this is also known as post-mortem interval (PMI). An international research team discovered that volatile organic compounds (VOCs) are what give off the smell of death. By using a pig to test this, the team found a mixture of families of molecules such as carboxylic acids, aromatics, and sulfurs. By finding the combination and quantities of these VOCs, Jean-François Focant states that “an odour fingerprint can be created for each stage of decomposition and possibly be used as an additional tool to estimate the PMI.” This method may not be 100% accurate, however it is more precise than previous methods.
Exhumation is the digging up of an already buried body. This may happen because there was some evidence that was overlooked or not completely analyzed. For example, some extra toxicological tests may need to be done, like testing the DNA and bone samples to see if the victim was poisoned. A body may need to be exhumed because some information that did not seem relevant at first may have become crucial. Finally, as research develops an exhumation may be requested since now the technology allows for more data to be collected, thereby helping the case.
When investigating a crime, a forensic scientist needs to evaluate everything that will help as evidence in the case. Some of the evidence collected by forensic scientists include body fluids, hair, fibres from clothing, paint and glass fragments, tire marks, and flammable substances. There are many instrumental techniques performed in order to examine body fluids; there are optical methods and separation analyses methods. In court, a mass spectrometry is the best source of evidence. Mass spectrometry is a method to find the molecular makeup of a sample by ionizing the sample thereby separating it into individual ions. Mass spectrometry is useful for toxicological analyses, trace evidence, arson investigations and explosive residue.
By using the tissues or bodily fluids of the victim as a sample, a forensic scientist can find if there were any toxic substances present and the concentration of them. They can then find out if the victim was on any medication or if they were poisoned. Carpet fibres, glass splinters, or paint flakes found on the victim can be used as a sample to find the exact dye mix, glass fragment, or polymers present. The investigators can then find who the manufacturer is to then narrow down the possible scenes of the crime. A mass spectrometry can determine the makeup of an accelerant by taking the residue as a sample. If any unique or exotic compounds are present and another crime scene is found to have similar makeup, then a connection between the crimes is made and can help identify a serial arsonist and/or criminal. Finally, a mass spectrometry can identify the materials of a bomb by taking the residue as a sample. The results can help investigators find out where the materials came from.
Forensic science does not only involve chemistry, but a combination of the sciences. However, many of the tests conducted require knowledge in chemistry. Chemistry helped the advancement of this field and the technologies involved in it. Mass spectrometry involves the breakdown of molecules by ionizing them, this test is the best source of evidence in court. And so it is evident that a career in forensic science is related to chemistry.

References
19-4092.00 - Forensic Science Technicians. (n.d.). Retrieved June 13, 2015.
Claridge, J. (2015, March 31). Asphyxiation. Retrieved June 15, 2015.
Claridge, J. (2015, April 2). Exhuming a Corpse For Forensic Analysis. Retrieved June 15, 2015.
Forensic Chemistry - American Chemical Society. (n.d.). Retrieved June 13, 2015.
Forensic Science Technicians. (2014, January 8). Retrieved June 13, 2015.
Forensic scientist: Job description. (2014, December 13). Retrieved June 13, 2015.
Forensics Hall of Fame: 10 Forensic Scientists Who Made History ». (2015). Retrieved June 13,
2015.
Kazmeyer, M. (2015). What Is Mass Spectroscopy Used for in Forensic Science? Retrieved June
15, 2015.
Knowles, R. (2014, June 25). 'Smell of death' reveals cadaver's secrets. Retrieved June 15, 2015.
Roberts, G. (2007, August 20). Lethal witness: How legendary pathologist Bernard Spilsbury's evidence was often fatally flawed. Retrieved June 13, 2015.
Visible Proofs: Forensic Views of the Body: Galleries: Biographies: Mathieu Joseph Bonaventure Orfila (1787–1853). (2006, February 16). Retrieved June 13, 2015.