The Smell of Death: Confirming Decomposition using Volatiles in the Air

Odour mortis, or the ‘smell of death’, refers to the chemicals released from the body during decomposition. Renowned forensic anthropologist Arpad Vass, who has studied the chemical changes occurring in the body after death for many years, recently shared the details of a particularly interesting scenario. The article, published in the May 2019 issue of Forensic Science International, details a fascinating case in which the occurrence of human decomposition was demonstrated based solely on chemical compounds in the air for the first time, without any human remains actually being found at the scene. The article doesn’t specify suspect or victim details, but anyone familiar with the case will recognise it instantly.

First, a brief introduction. In 2008, a woman was charged with the murder of her daughter, allegedly storing the victim’s body in the boot of her car for several days before disposing of the remains and dumping the car. Police had initially been alerted to the incident by the suspect’s parents, who had picked up their daughter’s abandoned car and noticed a foul decomposition-like odour coming from the vehicle. Coupled with the fact they had not seen their granddaughter in several weeks, the suspect’s mother promptly called 911.

The police soon took possession of the car and agreed that the scent of decomposition was emanating from the vehicle. Numerous cadaver dogs, specifically trained to detect odours from decaying bodies, alerted to the back of the car, further suggesting some kind of decomposing remains had been stored in the boot of the car. Fly pupae were also discovered. Entomological evidence is frequently associated with decomposing human remains, with flies and various other insects known to visit corpses to feed or lay eggs. Although no human remains were found in the car, several weeks later the body of the missing girl was found in a wooded area near the suspect’s home, and the case promptly turned into a murder investigation, with the victim’s mother as the prime suspect. However with minimal physical evidence linking the body to the suspect’s car, law enforcement turned to a somewhat unconventional tool to aid their investigation.

Various pieces of evidence were recovered from the vehicle, including segments of carpet, scrapings from the tyre wells, and various pieces of rubbish found in the car. Interestingly, investigators also collected some air samples from the boot of the car. Air can be sampled from remote locations using a technique that utilises air pumps to draw in gaseous analytes from the environment and capture them in a sorbent trap. This collection of trapped compounds can then be transported to a laboratory for analysis. In this case, about 35L of air was collected from the vehicle into a type of sorbent tube, then analysed using gas chromatography/mass spectrometry (GC/MS). GC/MS is a well-established analytical technique, allowing scientists to separate the individual chemicals in a mixture and identify those components. You can read more about how mass spectrometry works here.

This process allowed researchers to figure out exactly which volatile chemicals were present in the suspect’s vehicle and establish whether these are everyday compounds likely to be found in a car, or if they had some other source.

In the years leading up to this case a great deal of research had been conducted at the University of Tennessee’s Anthropological Research Facility. At this facility researchers were investigating, among other things, the odours produced during the decomposition of a human body. The odours created during this process are the result of volatile compounds produced as the body decomposes, and research has demonstrated that hundreds of individual chemical components are formed during this complex process. As part of research at the university, researchers had constructed a vast database of hundreds of chemicals detected during the process of human decomposition, including the different decomposition stages at which those chemicals appear. By comparing the chemicals detected in the vehicle with those stored in the database, it was possible to identify compounds known to be produced during the decomposition process. There was an 80% match between the compounds detected in the boot of the car and those chemicals considered to be relevant to human decomposition. Furthermore, unusually high levels of chloroform were also detected in the boot of the car.

The results from the air samples collected and chemical extracts from various other artefacts in the car led the researcher to conclude that there was a very high likelihood of a decomposition event occurring in the boot of the car. Many of the compounds detected in the vehicle could only be logically explained by the presence of decomposing remains.

Despite these findings (and various other pieces of evidence presented in court), the jury reached a verdict of not guilty for the charge of murder. Not too surprising an outcome, considering the use of air analysis to detect decomposition had not previously been used in a legal investigation. However in closing arguments, the defence stated that the victim had in fact been placed in the vehicle for transport (claiming the victim’s death had been accidental), ultimately confirming the results of the analysis.

 

Vass, A. A. Death is in the air: confirmation of decomposition without a corpse. Forensic Sci. Int. (2019). doi:10.1016/j.forsciint.2019.05.005

Vass, A. A. Odor mortis. Forensic Sci. Int. 222, 234–241 (2012).

 

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Interview with Lecturer in Forensic Science Dr Kayleigh Sheppard

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Dr Kayleigh Sheppard works as a lecturer in forensic science at Liverpool John Moores University.

What is your current job role and what does this entail?

I currently work as a lecturer in Forensic Science at Liverpool John Moores University. My role is divided between lecturing undergraduate and postgraduate students, supervising undergraduate and MSc research projects and conducting research. I teach students across a range of undergraduate courses including BSc Forensic Science, BSc Forensic Anthropology and BSc Policing with Forensics, as well as postgraduate students on the MSc Forensic Bioscience course. Across these courses, I deliver a range of lectures and practical sessions focusing on topics such as Crime Scene Investigation and Forensic Methods with a particular focus on the photography of crime scenes and the evidence contained within them. Photography techniques covered include crime scene photography using natural light and flash, and more advanced photographic methods such as oblique lighting, alternate light source photography and automated 360◦ photography. I introduce the topics and theoretical principles of each topic to the students through lectures and workshops and then give the students hands on experience and the opportunity to develop their practical skills for each of the techniques through practical classes.

The practical classes delivered consist of fingermark enhancement, recovery and comparison, footwear mark recovery, evidence packaging techniques and crime scene documentation and photography. In addition, the students put together everything they have learnt throughout the semester and demonstrate their crime scene investigation techniques using simulated crime scenes that we are able to mock up within our crime scene houses. I supervise a range of student projects at both undergraduate and masters level which investigate advanced photographic methods of crime scenes, using 360-degree photography or mobile technology.

What initially attracted you to your particular field of research?

I have always had an interest and passion for the sciences, particularly biology and chemistry and knew that my future career would be in a scientific field. Whilst at school I was a keen problem solver and enjoyed reading crime and true crime novels. The combination of these traits led me to investigate a potential career in forensic science and so I started my BSc in Forensic Science at Staffordshire University. Throughout the course I was particularly interested in the crime scene aspects and envisaged myself going on to work as a crime scene investigator in the future. Upon completion of my course I had the opportunity to undertake a placement with Staffordshire Police. The placement allowed me to put my knowledge from my degree into practice, alongside crime scene investigators, whilst also providing me with the opportunity to conduct a research project. This project focused on my interest in crime scene investigations whilst incorporating emerging technologies- another interest of mine. The project was entitled “Next generation crime scene recording and forensic data use within criminal investigations”. The project was so well received by the Forensic staff that I wanted to pursue this area further and applied for a PhD investigating the use of 360-degree panoramic photography in a forensic context at Staffordshire University.

Alongside my PhD I was able to teach undergraduate students, introduce them to 360◦ camera technology, and provide them with hands on experience using the technology. The ability to apply my research into the curriculum to enhance the students learning sparked my interest in academia. An academic position provides the best of both worlds, allowing me to pass on my knowledge and experience to the students and teach them about forensic science, whilst also allowing me to continue to pursue my own research avenues. It is very rewarding to teach the students about modern and emerging technologies to assist with criminal investigations and to see their enthusiasm about a topic they may not have been introduced to before. The best part about being a lecturer is having the ability to teach students about topics they are unfamiliar with and pass on that knowledge. The most gratifying part of my job is when a student does not understand a topic or does not enjoy it, but through explanation and discussion using different learning techniques, the students understand the topic and begin to enjoy it.

Can you tell us about the research you’re currently involved in?

Most of the research that I conduct investigates the use of 360◦ panoramic photography for documenting and presenting crime scenes. At first, the research sought to validate the technique, regarding its accuracy for taking measurements at a scene. The research has begun to adapt the technology to answer specific research questions, which may aid crime scene investigators at the crime scene, by adapting the technology to make it do something that it could not do before.  For example, the 360◦ camera has been adapted to include alternate light sources for the detection of biological fluids, which are invisible to the naked eye, to simultaneously detect and document them in situ at a crime scene. Further research has also looked into the extent to which modern technologies for documenting crime scenes have been utilised for the presentation of evidence in the courtrooms and the factors that may be affecting the use in courtrooms.

The use of alternate light sources has also branched into other research avenues within the forensic field. Current research being conducted investigates the importance of cleanliness and prevention of cross contamination within Sexual Assault Referral Centres (SARC). The issues with identifying contamination in SARC environments is that in order to ensure cleanliness, the contaminants would ideally be visible.  Many biological fluids are invisible to the naked eye and therefore we cannot see them – so how do we know whether they are present on a surface or not? Most biological fluids fluoresce under specific wavelengths of light and enable them to be visualised. Research currently being conducted is seeking to determine the effectiveness of a SARCS-LED light source (CopperTree Forensics Ltd.) for identifying human blood, semen, saliva and vaginal secretions in small volumes (less than 1 μl) on a variety of surfaces typically encountered in SARC facilities. A SARCS-LED enables staff to ‘see’ biological traces, so provides a more targeted forensic clean. This layered approach alongside current ATP testing, and improved cleaning methods, can help to deliver a more thorough service. Using such a light source to identify biological fluids or contamination should enable a more effective cleaning protocol to be employed within SARC facilities, providing a more robust anti-contamination process which is in line with the Forensic Regulator expectations.

Research Figure

Semen and vaginal secretions deposited onto a white vinyl surface. Left – observed under natural light and the biological fluids are not visible to the naked eye. Right – observed under a blue SARCS-LED (445 nm wavelength) and demonstrating biological fluid fluorescence.

What are some of the biggest challenges in your area of research?

Academia can be a challenging place to work and trying to make sure that you maintain the knowledge of the forensic science field whilst it is continually updating can be challenging and often involves lots of reading to stay current, as well as attending training courses and conferences. High profile criminal court cases in forensic science are particularly interesting as they demonstrate to the students the importance and real world impact of their degree and the work they will be conducting in the field, so it is important to stay on top of these as well. At such an early stage in my academic career, being only 26, I felt as if there was a lot of pressure to prove myself worthy. As a result, I take advantage of every opportunity that is presented to me to further my knowledge and experience. It can be challenging to maintain a balance of lecturing, creating engaging and interesting sessions for the students, whilst continuing to conduct research and publish within the field. What keeps me going is my passion and enthusiasm for the subject area and the fact that I can shape the minds of the future.

Finally, do you have any advice for young scientists eager to pursue a career in your field of work?

For any individuals who want to pursue a career as a forensic scientist and get involved with any area of forensic science, make sure that you know what to expect. If you are simply going into this field because of your love for CSI: Crime Scene Investigation on the television that is not enough. The field of forensic science is not always as glamourous as it is often portrayed in the media, and some of the analysis techniques are not always conducted at the drop of a hat. However, saying that, forensic science is such an interesting and exciting field that is constantly evolving – no two days will ever be the same.

If you are interested in pursuing a career in this area you will need to make yourself stand out from the crowd. Over the past few years, this is a field which has become extremely competitive and you need to be able to demonstrate that you are a more suitable candidate than everyone else – what makes you different, what makes you stand out? In order to do this I would highly recommend getting any work experience that you can within the area. Working within criminal investigations can be tricky with active casework, but you do not know unless you ask. Some universities have partnerships with the local police forces so make sure to take advantage of any opportunities they can offer you. If this is not possible, try to get experience in laboratories to demonstrate your ability to follow protocols, work to standard operating procedures and avoid contamination. Alternatively, you could volunteer as a special constable within the police or assist within other police departments. Many of the skills that you obtain from these experiences can be transferred into the forensic field and more importantly demonstrates your commitment to enhancing your knowledge and skill set.

Website: LJMU Kayleigh Sheppard

Twitter: @Kay_Sheppard1

 

Detecting Homemade Bombs & Explosives in Sweat

Detecting Homemade Bombs & Explosives in Sweat

Improvised explosive devices (IEDs) are often used in the implementation of terrorist attacks, for instance the 2005 London underground bombings, the suicide bomb attack during a concert in Manchester, and the 2015 Paris attacks. Unfortunately the components required for building these devices are commercially available and the bombs relatively easy to construct.

Many explosives leave a characteristic trace after being handled or detonated, and it is essential that investigators can rapidly identify the components used in homemade explosives. Furthermore, the ability to trace the explosives back to particular individuals and terrorist cells is essential in preventing future attacks. Unfortunately effectively detecting and tracing explosives and explosive precursors can prove difficult. On top of this, after the production and implementation of IEDs, it can be difficult to prove a suspects’ involvement in bomb construction.

Researchers at King’s College London and Northumbria University have been working on developing new ways to detect homemade explosives.

The newly developed approach, recently published in the journal Analytica Chimica Acta, uses a technique known as ion chromatography high resolution mass spectrometry (IC-HRMS) to separate and detect chemical components. By applying the technique to compounds commonly encountered in the analysis of explosive residues, the method was shown to be effective in detecting a large number of components used to make bombs, capable of detecting just trace amounts of the chemicals faster than previous techniques.

Upon developing this method, the team of researchers then demonstrated that the approach could be applied to the analysis of human sweat, with the aim of indicating an individual has recently handled explosives. Participants were made to handle Pyrodex powder, a black powder propellant used in firearm cartridges. After handling the powder for a few minutes, palm sweat and fingermark samples were then collected at numerous timepoints over several hours. Analytes related to the explosive material were readily detected using the method. The real-world implementation of this technique could help prove contact between a suspect and explosive material or explosive precursors.

 

Gallidabino et al. Targeted and non-targeted forensic profiling of black powder substitutes and gunshot residue using gradient ion chromatography – high resolution mass spectrometry (IC-HRMS). Analytica chimica acta. 2019, In Press.