Sex Determination Through the Chemical Analysis of Fingerprints
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Sex Determination Through the Chemical Analysis of Fingerprints

Fingerprints have been a staple of forensic science for decades, providing a reliable (though not perfect) means of identifying suspects and placing people at crime scenes. In recent years, scientists have turned their attention towards exploring the additional information that could be extracted from fingerprints, in particular, chemical information for police intelligence. Fingerprints are composed of a mixture of chemical compounds both excreted through our skin and picked up from the environment.

Over the past decade, analytical chemists have shown that there may be sufficient chemical differences in the fingerprints of male and female donors to differentiate between the sexes. By studying these chemical differences, it may be possible to build a model capable of predicting the sex of a fingerprint donor based on the chemical compounds within the fingerprint.

In a recent study published in Forensic Chemistry, a method was developed to predict the sex of a donor based on the presence of peptides and proteins in fingermarks. The study used MALDI-MS (Matrix-assisted laser desorption/ionization mass spectrometry), a type of mass spectrometry that enables both the measurement and identification of the chemical constituents in a material, in addition to the imaging of samples. MALDI has already been demonstrated to be a powerful technique in the chemical analysis of fingermarks, including imaging fingermarks and detecting the presence of blood and drugs in the mark. Much of the research in the area has been led by Professor Simona Francese of Sheffield Hallam University in the UK, senior author on this recent paper.

In the study, 199 participants donated multiple fingermarks, culminating in hundreds of samples for analysis. The fingermarks used for the analysis were natural, that is to say, deposited with no fingertip preparation beforehand. Many studies in the chemical analysis of fingerprints use “groomed” marks, in which the fingers are rubbed on the face or forehead in order to load the fingers with skin secretions prior to deposition. Although this provides rich samples for analysis, they are not applicable to fingermarks encountered in the real world.

After fingermark collection, MALDI-MS was then used to analyse the samples, focusing on the measurement of peptides and proteins in the deposited marks. To further mimic realistic scenarios, fingermarks were analysed both undeveloped and enhanced by common fingerprint visualisation techniques (white powder and vacuum metal deposition). Based on the chemical profiles produced, a predictive model was then constructed for the purpose of predicting the sex of the donor of unknown fingermarks, such as those that may be discovered at crime scenes.

The technique had a predictive power of up to 86%, demonstrating the potential to differentiate between male and female donors to a degree. There were, however, challenges in this study. Polyethylene glycol (PEG)-based contaminants, routinely used in cosmetics and personal care products, were commonly encountered, interfering with the detection of the actual targets of the analysis. Furthermore, the application of fingermark development techniques also caused interference, with many mass spectra being dominated by the gold nanoparticles used in the vacuum metal deposition method. This suggests the technique may only be truly applicable in the case of undeveloped fingermarks.

Although the technique has a high predictive power, it was not able to determine the sex of the donor in all cases, rendering it unsuitable for conclusively excluding suspects from an investigation based on their sex. However the method could be used to triage fingermarks, allowing investigators to establish which marks are of the greatest importance and which should be prioritised for further study, potentially speeding up forensic investigations.

 

Heaton & Bury et al. Investigating sex determination through MALDI MS analysis of peptides and proteins in natural fingermarks through comprehensive statistical modelling. 2020, Forensic Chemistry, DOI: 10.1016/j.forc.2020.100271

Speeding Up Sexual Assault Investigations with Chemistry
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Speeding Up Sexual Assault Investigations with Chemistry

A recent study has demonstrated a new technique for the rapid detection of semen and the chemical differentiation of condoms, offering a new potential tool to assist sexual assault investigations.

Hundreds of thousands of cases of sexual assault and rape are reported each year, though this is undoubtedly a fraction of the actual number. The successful identification and prosecution of offenders in sexual assault cases often hinges on the ability to detect and collect biological fluids such as semen, essential for supporting victim statements and identifying the offender. In the past, the identification of semen has relied on destructive, non-specific presumptive tests, often based on a colour change reaction in the presence of a specific chemical in semen. In recent years, there has been a push for the development of preparation-free analytical techniques that could be used for the analysis of sexual assault evidence at crime scenes or in hospitals.

In a recent study published in Forensic Chemistry, a method using ambient ionisation mass spectrometry has been developed for the analysis of sexual assault evidence, specifically semen and condoms. Ambient ionisation MS refers to a type of mass spectrometry which allows the rapid, direct analysis of a material, eliminating the need for the time-consuming and destructive sample preparation steps that limit traditional techniques.

This particular technique, called sheath-flow probe electrospray ionisation MS, uses a small, cheap-to-construct probe that is simply touched to the surface of the sample. The probe is then placed in front of a mass spectrometer inlet and a voltage applied to produce an instant unique chemical profile. In all, a sample can be analysed in a matter of seconds.

In this study, semen was successfully detected on various materials, such as fabric and condoms, mimicking the kind of environments the body fluid could be encountered during a sexual assault investigation and, crucially, showing the ability of the technique to work with different surfaces. Whereas presumptive tests for semen are focused on the presence of one chemical, making them prone to “false positives”, this new technique harnesses a suite of chemicals, allowing a more confident identification of semen. It was also shown that semen could still be detected after 40 days of ageing. This is important as during a criminal investigation it may be days, weeks or even longer before evidence is seized and analysed. After 40 days, the chemical profile was remarkably unchanged, indicating that even older semen could potentially be identified.

The study then took this technique one step further, applying it to the analysis of condoms. As criminals become more knowledgeable about forensic evidence such as DNA, there has been an increase in the use of condoms by criminals to protect their identity. By analysing the surface of different brands and types of condom, it was demonstrated that unique chemical profiles were associated with the different condoms, with notable chemicals relating to the condom’s material or flavouring being detected. This has two major implications. Firstly, the ability to detect lubricants and traces from condoms could prove beneficial in confirming condom use, particularly important when biological evidence is lacking. Furthermore, the unique chemical profiles could even open up the possibility of indicating what type of condom was used by the offender, offering more information to the investigation.

Direct analysis techniques such as this have great potential to speed up forensic investigations, but it will no doubt be years before such technology is considered for adoption by police forces.

 

Rankin-Turner et al. Using mass spectrometry to transform the assessment of sexual assault evidence. Forensic Chemistry, 2020, DOI: 10.1016/j.forc.2020.100262

If you don’t have a subscription to Forensic Chemistry, see the 50-day free access link or get in touch with the authors.

Fingerprint Technology to Prevent Pangolin Poaching
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Fingerprint Technology to Prevent Pangolin Poaching

Pangolins are amongst the most illegally trafficked mammals in the world, with hundreds of thousands being slaughtered each year for their meat and scales. In recent months, pangolins have gained extra attention due to their link to the spread of COVID-19, resulting in the Chinese government making efforts to control the use of pangolin scales in traditional medicine. All eight species of pangolin are protected and included on the International Union for Conservation of Nature’s Red List of threatened species, but this does not deter criminals from capturing and selling these animals.

In recent years forensic techniques have been harnessed in the fight against poaching and illegal animal trafficking, in particular with the aim of linking illegally traded animal materials to the perpetrator. Materials derived from animals pose a particular challenge for traditional fingerprinting techniques, with techniques often not being suitable for use on the likes of scales, feathers and skins of animals. Furthermore, in order for fingerprint development and collection techniques to be rolled out across relevant countries, the tools developed need to be easy to use, effective and inexpensive.

In a recent study published in Forensic Science International, a team of researchers at the University of Portsmouth developed a technique for lifting fingermarks from the scales of pangolins, demonstrating the potential to connect criminals to illegally traded pangolins via fingerprints. As an individual pulls scales from a pangolin, it is likely that fingermarks will be deposited on the scales. However, determining the best development technique for this unique material can be challenging.

The technique presented employs lifters which contain a soft gelatine material ideal for picking up traces and impressions when pressed against a surface. Low-adhesive gelatine lifters have been used in forensic practice for decades, particularly for lifting footwear marks and fingermarks off objects, but have not been widely applied in wildlife crime. The surface of a pangolin scale is uneven, containing voids that could be problematic for some development techniques. However, the soft nature of the gelatine allows the lifters to press into the voids and lift as much material as possible.

In this study, scales from varying African species of pangolin were provided by the UK Border Force for the assessment of the gelatine lifting technique. Of the marks lifted from pangolin scales, 74% exhibited ridge detail and 24% showed no ridge detail but evidence of contact. Once lifted, the fingermarks could then be imaged using a camera or mobile phone camera for rapid digitisation. Although only a pilot study, the research has demonstrated that the gelatine lifter could be easily applied to the scales of the pangolin and subsequently preserved for scanning and comparison, providing law enforcement with a potential route to identify poachers.

 

Moorat et al. The visualisation of fingermarks on Pangolin scales using gelatine lifters. Forensic Science International, 2020. DOI: 10.1016/j.forsciint.2020.110221

 

 

Smoker or Non-Smoker? Donor Characteristics from Saliva
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Smoker or Non-Smoker? Donor Characteristics from Saliva

The discovery of body fluids during forensic investigation can provide countless clues to a crime. Saliva is often countered during certain investigations, particularly in the investigation of sexual assaults and other violent crimes. The wealth of chemical information housed in the complex matrix could provide clues as to who might have left the substance behind. One example of this is whether or not the donor is a smoker.

A team of researchers at the University at Albany have hit the news multiple times in recent years with their rapid, on-site tools for body fluid analysis. Using Raman spectroscopy, the group have successfully developed methods to identify body fluids, estimate body fluid age, and determine characteristics of the donor, such as race and sex. In the latest paper by Igor Lednev and his colleagues, published in Journal of Biophotonics, Raman spectroscopy has been shown to differentiate between smokers and non-smokers.

Working in collaboration with researchers at Kuwait University, the team applied Raman spectroscopy to dried saliva from smokers and non-smokers, aiming to use chemical differences in the samples to determine whether or not the donor smokes. Raman spectroscopy is a non-destructive technique that enables the rapid, on-site analysis of samples, producing distinctive chemical fingerprints consisting of bands produced by the interaction of light with molecular structures.

One might assume the test would target nicotine, a major chemical component in tobacco. However, nicotine is relatively short-lived in the body, thus is not a suitable target for analytical tests. Instead, the researchers focused on cotinine, a primary metabolite of nicotine with a notably longer half-life. Saliva samples from 32 donors were analysed by Raman spectroscopy and the chemical profiles produced studied for differences. Researchers soon encountered a problem. Raman bands indicative of cotinine overlapped with typical Raman bands produced by saliva, making the detection of cotinine in saliva challenging. The team used machine learning to solve this problem.

First, they identified eight spectral regions that contributed the most variation between the saliva of smokers and non-smokers. Using an artificial neural network, a classification model was constructed for the prediction of smoking habits of a donor. By inputting chemical data from known samples, the network is able to learn from the data in order to predict an output (in this case, whether or not the donor of a saliva sample was a smoker). In laboratory-based studies, the model constructed achieved an impressive accuracy of 100%.

Although this pilot study was based on a very limited sample size, the technique shows great promise in the determination of donor characteristics from dried body fluids.

 

Al-Hetlani et al. Differentiating smokers and nonsmokers based on Raman spectroscopy of oral fluid and advanced statistics for forensic applications. Journal of Biophotonics, 2019, DOI: 10.1002/jbio.201960123  https://onlinelibrary.wiley.com/doi/abs/10.1002/jbio.201960123

Maggot Analysis with Mass Spectrometry
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Maggot Analysis with Mass Spectrometry

A new proof-of-concept study by researchers at the University at Albany in New York has developed a mass spectrometry-based technique for the rapid species prediction of blow fly larvae for use in forensic investigations.

Entomological evidence (evidence relating to insects) has proven invaluable to forensic investigations for decades, particularly in the estimation of time since death. Insects which feed on decomposing remains, known as necrophagous insects, will colonise a body in a reasonably predictable pattern, with different insects arriving at different stages throughout the decomposition process. Different species of flies, beetles and mites are commonly encountered. Blow flies in particular will often arrive at the scene within minutes of death to lay eggs on the body. As these eggs hatch, larvae (or maggots) emerge to feed on the decomposing remains. By studying the type and age of insects present at a scene, it may be possible to estimate the time since death, or postmortem interval.

The ability to achieve this hinges on the correct identification of insect species, which is unfortunately not always straightforward. The larvae of different species of blow fly are visually very similar, thus difficult to distinguish by eye. For this reason, maggots are often reared to maturity for species identification, with adult blow flies exhibiting more distinguishing physical differences. Inevitably the rearing of maggots to adulthood is a time-consuming process that requires the expertise of a forensic entomologist.

In recent years, researchers have tried to develop more rapid approaches to insect species identification, particularly using chemical analysis. Researchers at the University at Albany in New York have been applying direct analysis in real time mass spectrometry (DART-MS) to the analysis of insect evidence to provide a rapid species identification tool. In DART-MS, the sample is placed between the DART ion source and the inlet of the mass spectrometer, allowing chemical components in the sample to be ionised and drawn into the MS for direct analysis. DART-MS requires minimal or no sample preparation and results can be obtained almost instantly. Using this technique, Rabi Musah and her team have already demonstrated the ability to determine the species of larvae, pupae and adult flies, highlighting a promising new tool in rapid species identification in forensic entomology.

However, until now this research has focused on the analysis of individual species. In a real-world scenario, maggots present on the body may consist of multiple different species, therefore any techniques developed for rapid species identification of larvae must be able to work with mixed samples. In a recent study, the team have taken the method one step further by examining the potential to identify larvae from mixed species.

Blow flies of various species were collected from Manhattan, New York. Maggots were submerged in 70% ethanol and the solution exposed to the ion source of the DART-MS to produce chemical signatures of both individual species and combinations of species. Mixtures of two, three, four, fix and six different species were analysed. Using the chemical profiles produced, a predictive model was constructed for the subsequent identification of unknown insect samples. Using this model, maggot species could be established with an accuracy of up to 94% and a confidence interval of 80-95%. Individual insect species are readily differentiated, with different species producing distinct chemical profiles. Similarly, mixtures of two different species could also be differentiated. As might be expected, samples containing a higher number of species were more difficult to differentiate.

Although only a proof-of-concept study and further validation is required, the study demonstrates that DART-MS could offer a way of rapidly determining the species of blowfly larvae, thus allowing investigators to establish which insects are present at the scene of a death and work out postmortem interval faster.

 

Beyramysoltan, S. Ventura, M. I. Rosati, J. Y. Giffen, J. E. Musah, R. A. Identification of the Species Constituents of Maggot Populations Feeding on Decomposing Remains—Facilitation of the Determination of Post Mortem Interval and Time Since Tissue Infestation through Application of Machine Learning and Direct Analysis in Real Time-Mass Spectrometry. Analytical Chem, 2020, In Press. 

Fingerprint Drug Testing to Detect Drug Use or Contact
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Fingerprint Drug Testing to Detect Drug Use or Contact

The detection and identification of drugs to demonstrate the use of illicit substances has long since been achieved through the collection and analysis of bodily fluids such as urine or blood. However with the inconvenience and invasiveness of collecting bodily fluids from people combined with the risks associated with handling biological fluids, scientists have examined alternative matrices for the detection of drug abuse.

In recent years researchers have demonstrated the possibility of detecting drugs in a less invasive manner, using only a fingerprint. In a recent study published in the Journal of Analytical Toxicology, researchers at the University of Surrey have developed a mass spectrometry-based technique to not only detect illicit drugs in fingerprints, but also differentiate between drug use and drug contact.

Fingerprints were collected from recent drug users undergoing treatment at a drug rehabilitation centre, specifically those who had taken heroin or cocaine in the last 24 hours. Fingerprints were collected both before and after thorough handwashing, with the aim of establishing whether drugs could be detected from both the surface of the hands but also in sweat excreted by the participants. Fingerprint samples were also collected from non-drug users who had simply handled heroin to further establish the detectable differences between those who have used or handled drugs. The fingerprints collected were analysed by liquid chromatography-high resolution mass spectrometry, with a focus on both the drugs and their metabolites (for instance 6-monoacetylmorphine, a compound formed in the body following heroin use).

The experiment successfully detected heroin or its metabolites in every scenario, even if an individual had washed their hands prior to fingerprint collection. However in some instances, the process of hand-washing removed all detectable traces of the drugs, such as in the case of morphine, acetylcodeine and noscapine. Importantly, the technique was able to distinguish between those who had handled illicit drugs and those who had actually taken them, due to the presence of metabolites only formed in the body following drug use. Furthermore, the research demonstrated that it was also possible to detect heroin in the fingerprints of someone who had simply shaken hands with another person who had handled heroin. This highlights an essential factor should such techniques ever become operational in the detection of drug use, stressing the importance of handwashing prior to fingerprint collection to ensure any drugs detected are the result of drug use rather than inadvertent contact with illicit drugs.

The ability to detect drugs in fingerprint could aid legal investigations in a number of ways. Firstly, by demonstrating drug use in known individuals through the analysis of their fingerprints. And secondly, by analysing fingerprints recovered from crime scenes to indicate a person of interest has recently used or handled illicit drugs, potentially guiding police investigations. The full study was published in the Journal of Analytical Toxicology.

 

Catia Costa, Mahado Ismail, Derek Stevenson, Brian Gibson, Roger Webb, Melanie Bailey, Distinguishing between Contact and Administration of Heroin from a Single Fingerprint using High Resolution Mass Spectrometry, Journal of Analytical Toxicology. https://doi.org/10.1093/jat/bkz088

Rapid & Safer Drug Testing with Mass Spectrometry
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Rapid & Safer Drug Testing with Mass Spectrometry

Scientists have demonstrated a new method that allows police to quickly predict the contents of suspected drugs packages using Direct Analysis in Real Time mass spectrometry.

When faced with a suspected illicit drug, police officers will not know the identity or potency of the substance. Investigators will often perform something called a presumptive test to indicate what kind of drug they are dealing with. These tests typically involve scooping up a small amount of the material and adding a few drops of a specific chemical reagent to the sample. If the drug is present, a chemical reaction will occur resulting in a distinctive colour change to indicate a positive result.

Unfortunately, these tests can be somewhat hazardous, necessitating both the potential exposure to harmful substances in order to sample the drug, as well as the use of chemicals in the field. This has become particularly problematic in recent years as more uncharacterised and potentially harmful illicit drugs have hit the market. For instance, recent news reports have seen first responders complain of exposure to the drug fentanyl, a particularly potent opioid harmful even in small quantities.

In light of this, the need for rapid, reliable and safe drug screening techniques is greater than ever before.

Researchers at the National Institute of Standards and Technology (NIST) have teamed up with Maryland State Police and Vermont Forensic Laboratory to develop a method of quickly predicting the contents of a suspicious package without the need to handle the contents. We’ve all seen how airport staff check luggage for traces of explosives. They swipe an absorbent material over the surface of the bag, introduce that swab to an analyser, and receive a rapid alert to the presence of specific controlled substances. This new method essentially follows the same process. Upon discovering a package suspected of containing illicit drugs, the investigator simply swipes an absorbent wipe across the surface of the package, and that swab is then exposed to the mass spectrometer.

The new method utilises Direct Analysis in Real Time mass spectrometry (DART-MS) analysis. DART-MS is a form of ambient ionisation mass spectrometry in which the sample is placed between the DART ion source and the inlet of the mass spectrometer, allowing chemical components in the sample to be ionised and drawn into the mass spectrometer for rapid analysis. The major advantage of this technique is that it requires no form of sample preparation, so the sample itself (or in this case a swab of the sample) can be analysed directly for almost instantaneous results. You can read more about how DART works here.

In a study recently published in the journal Forensic Science International, the technique was applied to almost 200 suspicious packages, including plastic baggies, pill bottles, envelopes, and tin foil bags. From these samples, a range of illicit substances were detected, including fentanyl, cocaine, heroin, methamphetamine and synthetic cannabinoids. Also detected on a couple of the packages was carfentanil, a particularly powerful opioid thousands of times more potent than heroin and a great concern for first responders. It was shown that only a few micrograms of drug on the outside of the packages could be detected. The study has successfully demonstrated the possibility of rapidly screening for the presence of harmful drugs such as fentanyl, even when mixed with other substances like heroin. In fact, the contents of the packages were successfully predicted 92% of the time.

This new technique enables police officers to rapidly screen suspicious bags and packages for the presence of illicit drugs, whilst reducing the risk of exposure to harmful substances. By quickly and safely predicting the contents of a package, steps can then be taken to ensure the evidence is processed under appropriate conditions, for instance in a laboratory fume hood and with appropriate protective equipment. Although a complete analysis by standardised laboratory methods would still be required for legal purposes, this new technique at least allows for the rapid, and safe screening of suspected drugs.

 

Sisco, E. Robinson, E. L. Burns, A. Mead, R. What’s in the Bag? Analysis of Exterior Drug Packaging by TD-DART-MS to Predict the Contents. For. Sci. Int., 2019, In Press.

 

Discovering Donor Characteristics from Bloodstains with Infrared Spectroscopy
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Discovering Donor Characteristics from Bloodstains with Infrared Spectroscopy

From interpreting the incident to pinpointing the perpetrator, the presence of blood at a crime scene can provide clues vital to solving a crime.  Since the advent of DNA profiling in the 1980s, police have been able to use DNA to link suspects to crime scenes, making the detection and collection of biological evidence more important than ever before. However successful DNA profiling relies on a positive match with either a DNA profile from a suspect or one stored in a database. With nothing to compare a profile to, the DNA is of limited use and the trail may quickly run cold.

But what if investigators could gain even more information from a bloodstain at a crime scene? What if it were possible to rapidly figure out whether the donor was male or female, or establish their race? And all of this without shipping samples back to the lab.

New research conducted at the University at Albany in New York has demonstrated that it may be possible to establish some individual donor characteristics in a matter of minutes.

Past research has already demonstrated that the biochemical composition of blood differs between males and females and individuals of different races. But the ability to obtain this information on-site at the crime scene in a matter of minutes could change the way body fluids are processed. In a recent study, Prof. Igor Lednev and his team applied a technique known as attenuated total reflection Fourier transform-infrared (ATR FTIR) spectroscopy to blood analysis, with the aim of establishing whether characteristics such as sex and race can be determined from bloodstains.

FTIR is an analytical technique capable of providing information about a material’s chemical information. In brief, the device directs infrared radiation towards the sample. Some of this radiation is absorbed by the material, and some passes through. The sample’s absorbance of this light at different wavelengths is measured and used to determine the material’s chemical information. After analysis a spectrum is produced, which acts as a kind of molecular ‘fingerprint’ of the sample. The different features in the spectrum relate to the different chemical components in the sample.

Infrared spectra were produced by analysing the blood of 30 donors (a mixture of male and females of Caucasian, African American and Hispanic racial origin). From this, researchers could observe any differences occurring between blood from male and females, and blood from members of different races. Using this data, the researchers built a model capable of classifying samples based on their chemical profile. By taking the chemical profile of an unknown bloodstain and comparing it with a model containing bloodstains from numerous different groups, the model can predict the likely classification (i.e. whether the donor was male or female and which racial group they belong to). In this study, it correctly classified bloodstains around 90% of the time.

Using infrared-based techniques has a number of advantages over other methods of analysis. As the technique simply necessitates the direction of light towards the bloodstain, the technique is non-destructive. Inevitably this is perfect for criminal investigations – destroying the evidence is never ideal. IR spectroscopy is also amenable to portability, lending itself well to on-the-go analysis at crime scenes and so potentially saving a lot of time by avoiding sending unnecessary samples back to the lab for analysis.

Although only a pilot study, this research has demonstrated the possibility of establishing donor characteristics through the rapid and non-destructive analysis of bloodstains. The ability to determine features such as sex and race would enable police to significantly narrow down the search for suspects or victims, ultimately preserving valuable time and money. Furthermore, the ability of FTIR to non-destructively analyse evidence on-site renders it an ideal tool for forensic analysis. Inevitably a great deal more research will be necessary, and if the technique ever becomes operational, it would be years before such technology and methods were suitable for deployment to crime scenes and use as evidence in criminal trials.

 

Mistek et al. Phenotype profiling for forensic purposes: nondestructive potentially on scene attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy of bloodstains. Forensic Chemistry. 2019, In Press.

 

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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