Geochemistry and Clandestine Graves

Geochemistry and Clandestine Graves

Perpetrators of fatal crimes will on occasion attempt to conceal their wrongdoings by burying the evidence – that is, attempting to bury human cadavers. This can be problematic during a forensic investigation for a number of reasons. Firstly, the search for a victim’s body may well be relatively blind, with investigators having little or no idea as to where a body has been buried. In some instances, a body may well be so damaged or decomposed that little recognisable human remains are present. The perpetrator may later remove the body from the burial site, perhaps fearing discovery, leaving behind no obvious trace that a body was ever buried there.

So what can investigators do to determine if an area of soil was the site of a clandestine grave (illicit burial site)? A number of methods that have been developed to tackle this question.

grave

Certain chemical compounds may be indicative of decomposing flesh. Sterols have been suggested as a potential biomarker for decomposition fluids – that is, the presence of them in soil could indicate whether or not a body has decomposed in that location, depending on the types of sterols present and in what amounts. Sterols are a class of organic compound, of which cholesterol is perhaps the most well-known sterol present in animal cells. This compound can be found in plants too, but in a significantly smaller amount, thus the unexpected presence of cholesterol in soil will typically indicate some kind of animal-related activity. Research examining the decomposition fluids in soils found sterols to be beneficial in this application (Von der Luhe et al, 2013). A number of pig carcasses were buried over a few months, with soil samples being collected from underneath the cadavers at different time points after burial. Cholesterol and coprostanol were detected in the soil, and it is these substances that were of particular interest to the researchers. Coprostanol is formed via hydrogenation of cholesterol in the intestinal tract of higher mammals, thus it is considered a useful biomarker associated with the faecal matter of animals such as humans and pigs. The concentration of these compounds was greater during the time period in which the pigs were undergoing the putrefaction stage of decomposition, at which point fluids would be leeching into the soil. This suggests a certain time frame in which these compounds are useful as indicators of decomposition fluids.

chol

Cholesterol

The research suggested that, as the cadaver decomposes, decomposition fluids leak into the soil, depositing cholesterol and coprostanol (and a whole range of other substances). Thus the presence of these compounds in a particular area of soil, particularly if nearby similar areas did not contain them, could indicate previous decomposition of a human (or equally a pig or other animal) in the area. However it is vital to note that these compounds could equally be detected in the soil as a result of faecal matter, though potentially in considerably lower concentrations than those produced by a whole decomposing body.

Other compounds resulting from decomposition are of equal interest in detecting potential gravesites. Adipocere, also known as grave wax, is an insoluble, white substance known to form if a body decomposes in very specific conditions. The presence of this substance in soil can of course indicate the decomposition of a body, but how does one distinguish between the decomposition fluids of a human and those of another mammal? Research has aimed to answer this question using isotopes (Bull et al, 2009). By focusing on the ratio of 13C to 12C content of particular fatty acids from the fats of various animals, it was suggested that it is possible to distinguish between adipose fats from humans and those from other animals, such as pigs, though further work may be required to develop this application.

Other researchers are applying existing forensic techniques in a novel manner to the detection of clandestine graves. When the body decomposes, a significant amount of nitrogen is released, typically in the form of ammonium and nitrate (Hopkins et al, 2000). Ninhydrin, a compound already readily available to law enforcement due to its use as a method of fingerprint development, can produce a blue or purple pigment upon reaction with certain nitrogen-containing compounds.

nin

Ninhydrin is typically used for visualising fingerprints (http://daten.didaktikchemie.uni-bayreuth.de)

One particular study examining ninhydrin reactive nitrogen (Carter at al, 2008) left a number of mammalian cadavers to decay over a period of a month, after which soil samples from the burial sites were collected and analysed for ninhydrin reactive nitrogen. This work discovered that cadaver burial resulted in the concentration of NRN in the soil approximately doubling, thus concluding that it may be possible to use ninhydrin as a presumptive test for gravesoil. Of course this particular method is somewhat limited by the fact that any mammalian cadaver (and plants or faeces for that matter) will most likely produce this increase in nitrogen-containing compounds which will react with ninhydrin, but an interesting application of an existing indicator nonetheless.

The various methods of using the chemical analysis of soil to detect clandestine graves are plentiful and fascinating. Despite the limitations, namely the possibility of animal faeces and non-human decomposition providing false positive results, these techniques may at the very least act as a kind of presumptive or complimentary test for possible burial sites.

References

Von der Luhe, B. Dawson, L. A. Mayes, R. W. Forbes, S. L. Fiedler, S. Investigation of sterols as potential biomarkers for the detection of pig (S. s. domesticus) decomposition fluid in soils. Forensic Sci Int. 230 (2013), pp. 68-73.

Bull, I. D. Berstan, R. Vass, A. Evershed, R. P. Identification of a disinterred grave by molecular and stable isotope analysis. Sci Justice. 49 (2009), pp. 142-149.

Carter, D. O. Yellowless, D. Tibbett, M. Using ninhydrin to detect gravesoil. J Forensic Sci. 53 (2008), pp. 397-400.

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Identifying Insects with Spectroscopy

Identifying Insects with Spectroscopy

Entomology, that is the study of insects, can provide vital information during a forensic investigation. After an individual dies their body begins to undergo a complex decomposition process almost immediately, attracting a variety of insects along the way who wish to colonise, feed on the temptingly putrefying remains and reproduce.

Specialists have been taking advantage of this fact for hundreds of years, allowing us to discover that the types of insects present on a cadaver and the age of these insects can prove invaluable in estimating how much time has passed since the victim died (known as the post-mortem interval). Simply put, certain species prefer the decomposing corpse at different stages in the decay process, and with the right information, investigators can study the insects and their ages and begin to develop a kind of timeline.

Currently, accurately identifying species and establishing the development stage of an insect can be time-consuming and requires the expertise of an entomologist and potentially DNA analysis. This is obviously not ideal – your average police force does not have an entomologist on hand, nor do they have oodles of times to dedicate to insect identification. Even with the assistance of an entomologist, accurately determining the age of maggots can be problematic. Although larvae may be of a certain age, their length and weight can be affected by a variety of factors that may not be accounted for, such as starvation (Singh and Bala, 2009).

As you might expect, researchers are searching for ways to resolve this issue, and analytical chemistry might just be the answer.

As analytical chemistry progresses and increasingly advanced analytical techniques are developed, we are seeing more and more fascinating applications of these instruments to established areas of study. In a recent study published in Forensic Science International, researchers took a well-established technique and applied it to forensic entomology. In this case, they used a form of infrared spectroscopy.

Infrared spectroscopy is an analytical technique which determines the amount of radiation absorbed by a molecule. Infrared light is directed towards to sample and, depending on the molecule, a certain amount of radiation will pass through the sample and some will be absorbed.  When a molecule absorbs radiation, the bonds within it begin to vibrate. Different bonds will vibrate and be influenced by surrounding atoms to a different extent, thus allowing for a unique ‘spectrum’ to be produced. This spectrum is essentially a graph displaying how much radiation was absorbed by the sample at what wavelength. Scrutinising this spectrum can allow the analyst to determine what kind of molecules are present. Although this is not sufficient to specifically identify compounds, the spectrum produced can at least be used to distinguish between different samples, which will produce different spectra. The spectra essentially act as ‘fingerprints’ for different substances.

FTIRSpectrum

Typical IR spectroscopy spectra.

If you want to know a bit more about this technique, Compound Chemistry has a great little page on IR spectroscopy.

So back to how this analytical technique can be useful in forensic entomology. The proof of principle study to which I’m specifically referring aimed to both identify the species of larvae and the life cycle stage using vibrational spectroscopy, in this case Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectroscopy. A slightly long-winded name, but in short this is simply a form of IR spectroscopy that allows in situ analysis of solid or liquid samples without the need for sample preparation. Anyone who has spent many painful hours preparing samples for analysis will appreciate the benefit of this.

Three species commonly encountered at incident scenes were used in the study; C. vomitoria, L. sericata, and M. domestica (that is the bluebottle fly, the green bottle fly and the common housefly respectively). One of these species (the C. vomitoria) was also selected for a study focussing on the life cycle, in which spectra were collected for each time point in the insect’s life cycle. Scans were based on a crushed mixture of epidermis and internal matter (not possible for a ‘no maggots were harmed during the making of’ notice then). The results were promising, indicating FTIR spectroscopy could be a great tool in forensic entomology.

But surely there is a whole range of analytical instruments out there (yes, there sure is), so why would this one be any more suitable for forensic entomology? One of the major benefits of FTIR is the possibility of handheld IR instrumentation, which basically means it can be used in situ at the scene of a crime or other incident. Granted the investigator would need the appropriate equipment, but it beats shipping samples back to the lab and waiting for analysis. IR spectroscopy is a non-destructive technique (okay, the insects were somewhat mutilated in this study, but nevertheless the samples themselves remained after analysis). The ability to perform analyses without destroying the sample has a huge benefit, particularly if the available sample is limited, allowing for alternative tests and future analysis to be conducted if necessary. This of course is an advantage in forensic science. Also of great benefit to a legal investigation, IR instrumentation is fast, with spectra being collected in a matter of minutes.

There is however the glaring problem of the cost of analytical instrumentation. As I previously stated, your average police force may not have a forensic entomologist on hand… they equally may not have the funds to purchase analytical instrumentation such as IR spectrometers.

Bearing in mind this was merely a pilot study, using a very limited sample size, the research shows some promising results – that it is possible to classify species and life cycle stage using IR spectroscopy. Were this to be expanded upon, you could theoretically develop a database of IR spectra collected from different species of insects at different stages of development, allowing future spectra obtained from unknowns to be compared and, hopefully, identified.

References

Pickering, C. L. Hands, J. R. Fullwod, L. M. Smith, J. A. Baker, M. J. Rapid discrimination of maggots utilising ATR-FTIR spectroscopy. Forensic Sci Int. 249 (2015), pp 189-196.

Singh, D. Bala, M. The effect of starvation on the larval behaviour of two forensically important species of blow flies (Diptera: Calliphoridae). Forensic Sci Int. 193 (2009), pp. 118-121.

Code of a Killer Competition

Earlier this week the much-discussed Code of a Killer aired in the UK, an extraordinary movie based on the true story of scientist Alec Jeffreys and the discovery of DNA fingerprinting. The DVD will be released on 20th April 2015, but until then we have a fantastic competition to win a copy. See below for details on how to enter.

COAK DVD 3D_small

Synopsis

From the Director of Broadchurch and the producer of Line of Duty comes Code of a Killer, out to own on DVD April 20th. The gritty telling of the extraordinary true story of Alec Jeffreys’ discovery of DNA fingerprinting and its first use by Detective Chief Superintendent David Baker in catching a double murderer.

David Threlfall (Shameless) takes the role of David Baker who, between 1983 and 1987, headed up the investigation into the brutal murders of two Leicestershire schoolgirls, Lynda Mann and Dawn Ashworth. Only a few miles away, Dr Alec Jeffreys, played by John Simm (Prey), was a scientist at Leicester University who, on 10 September 1984, invented a remarkable technique to read each individual’s unique DNA fingerprint.

COAK DAVID 12 copy

If you didn’t have chance to catch it on TV, Code of a Killer will be released on DVD on 20th April. Click here to pre-order your own copy from Amazon now!

Competition time! Want to win your own copy of Code of a Killer? Then simply head on over to Twitter and retweet the below message to be in with a chance to win. Please note this is only open to those in the UK.

Careers in Forensic Science – Hints & Tips

Careers in Forensic Science – Hints & Tips

Aspiring forensic scientists are constantly asking questions about the ideal subjects to study at school, the best degree courses out there, how to find work experience and who will give them a job at the end of it all. The field of forensic science has become a popular and competitive one for an assortment of reasons, but there’s surprisingly little advice for students looking to get their foot in the door and seize their dream job. This post is going to offer a few hints and tips that might just be useful for the budding forensic scientist.

What to Study? So Many Choices!

So you want to work in forensic science. But what qualifications do you need in the first place? Prior to undergraduate study, your choice of subjects can be fairly flexible, though it is advisable that you plan ahead and research the subjects required to gain access to your ideal university. Different universities have different requirements, but most forensic science degrees (and of course chemistry, biology, and any other science subject) will require you to have prior qualifications in chemistry and/or biology and perhaps maths. Even if a particular course doesn’t insist that you have a qualification in maths, any job in science is most likely going to require you to crack out your mathematics skills every now and then, so it’s certainly a subject worth studying.

fswhattostudy

The ideal degree programme is very dependent on the type of job you are looking for and, let’s be honest, there is a certain amount of ambiguity when a person states that they want to work in ‘forensic science’. I find a lot of people who make enquiries are actually envisioning a very ‘CSI-style’ job involving scene of crime management and investigation. If this is what you have in mind, this is a whole other career path that I’m not going to talk about here.

If, however, you’re envisioning a more laboratory-based role, you have a lot of options with what to study. There are many specific forensic science degrees available, the content of which can vary wildly. Some are extremely chemistry or biology-focussed, with the odd module in law and other sciences included. This type of forensic science degree will perhaps be most appealing to students fantasising about a career in forensics, and that’s fine. But there are a few things to keep in mind.

If you’re opting to take the forensic science degree route, be very wary that some courses are a lot more crime scene investigation based rather than science-focussed, so be sure to closely examine the modules available to you and choose a course that best suits the career you are imagining. No chemistry-based forensics lab will hire you if you haven’t taken a single chemistry module at university. A forensic scientist will typically specialise in a certain area of work, such as DNA analysis or toxicology, so you can choose a degree programme that is tailored to the specific field of work you are interested in. As for deciding which university hosts the “best degree course”, the Chartered Society of Forensic Sciences (CSoFS) offers a list of universities and degree courses that are accredited, based on certain standards outlined by the society.

A forensic science degree is by no means your only option. Many people will opt for pure science degrees such as chemistry or biology (in fact some might argue that this route of study is superior to a forensics-based degree), potentially followed by postgraduate study in forensic science. This route can widen your job prospects, particularly beneficial if you decide during your undergraduate studies that you would actually like to pursue a career in another field of science, which many forensic science students actually end up doing. If you’re interested in computer forensics, then obviously this will involve an entirely different route of study. Again, I won’t cover this here because we’ll be here all day.

How do You Get This Pesky Lab Experience?

A commonly-encountered problem in the job-hunting field, and this stands true across all fields of science and beyond, is the requirement of work experience. A lot of postings for job vacancies list prior laboratory experience as desirable if not essential for the role. Though you may have a certain amount of lab experience from your university studies, how do you expand on this and gain further experience that will set you apart from the other applicants?

fsexp

There are plenty of options available here. Essentially you want to be contacting potential employers who would be willing to take you on as a short-term work experience candidate (unfortunately typically unpaid work) or, if you can, find paid part-time or temporary work. You can get in touch with your local police force or private forensic service providers, but realise most will be unwilling to offer placements simply due to the nature of the work. And this is something I am sure you can understand – no one wants untrained, unqualified members of the public hanging around at a crime scene or near vital pieces of forensic evidence. But good news for you, this work experience does not have to have anything to do with forensic science – any laboratory work can provide you with beneficial experience, whether it be in a university, the pharmaceutical industry or even in a hospital lab. Regardless of whether the work placement is directly related to your future ideal career, there is a lot to be said for simply understanding how labs are managed, gaining vital health and safety knowledge such as following COSHH (Control of Substances Hazardous to Health) regulations and how to write a risk assessment, not to mention learning about general lab etiquette. And that’s not even mentioning the actual skills and procedural knowledge you can pick up. So don’t be mistaken in thinking work experience is useless unless it is based around forensic science, because that is certainly not true. So get contacting labs in your area and see what they have available.

Now that isn’t to say all employers will insist that you have previous experience – some positions are specifically tailored to new graduates for instance and will include on-the-job training. But even if you are applying for entry-based graduate jobs, any experience you can get will only help set you apart from other applicants, especially when you know there will be quite a lot of competition.

All the Benefits of Professional Memberships

fsstudyYou may or may not be aware of the many professional organisations worldwide that offer membership schemes, the most obvious in this case being the Chartered Society of Forensic Sciences (UK) and the American Academy of Forensic Sciences (US). The potential benefits of becoming a member of one of these professional bodies forms a long list. Holding membership with such an organisation provides you with great links for networking and meeting potential employers, as they often host events and conferences to which members are invited. They can be great for finding out about job opportunities, for instance the aforementioned CSoFS now only permits members to view job listings. Furthermore, they help you keep up to date on the latest research, as many provide their members with publications.

Are you hoping to become involve in a more specific field of work within forensics? Chances are, there is probably a professional body relating to that field of work too, such as the British Association of Forensic Anthropologists and the United Kingdom and Ireland Association of Forensic Toxicologists. The list is endless and offers so many benefits that it’s worth looking into. If you’re a student or not yet a forensic science professional, membership fees are typically not too high either.

Where Are All the Jobs?

So now we come to the million dollar question. How do you find a job in forensic science? Forensic science services will differ between different countries, but in short you will be looking at either private forensic service providers or individual police force labs. Many of these will advertise vacancies only on their company websites, some will use recruitment agencies (though from what I have seen, forensics jobs don’t appear on your average job-hunting site too often), or via professional membership bodies as previously mentioned. More recently, more and more jobs are being advertised on LinkedIn which, even if you don’t plan on using it for job-hunting, is a great website to be a part of simply for the sake of networking and showing off those skills and qualifications you’ve gained. Some employers have confessed to checking out an applicant’s LinkedIn profile during the shortlisting process.

But ultimately, finding and securing a job in forensic science, as in any field of work, requires a lot of persistence and patience. Keep an eye out for job vacancies on a daily basis, network as much as you can, and keep applying. Try to not become too disheartened in applying for job opportunities. Remember that every vacancy attracts dozens if not hundreds of applications, so there’s some fairly heavy competition, particularly in forensic science.

Good luck, future forensic scientists!

Forensic Case Files: Bruce Ivins and the Anthrax Attacks

Forensic Case Files: Bruce Ivins and the Anthrax Attacks

In September 2001, when the US was still reeling from the notorious 9/11 terrorist attacks, two US Senators and various media organisations were sent letters containing spores from the bacterium Bacillus anthracis, the cause of the disease Anthrax. The malicious mail resulted in the deaths of five people, the infection of 17 others and an investigation between the FBI and the US Postal Inspection Service that spanned almost 7 years.

Bacillus anthracis is a rod-like bacterium which can, upon entering the body, bring about the acute disease known as Anthrax. The endospores (spores) of the bacterium can lay dormant for years, but become activated and multiply after coming into contact with a host. Once contracted, the symptoms of the disease are dependent on the route by which the bacteria entered the body. However left untreated, the disease can ultimately kill the host.

The mailed anthrax spores were accompanied by misleading letters suggesting the attack was motivated by religion, though the prospect of terrorist groups, that were already at the forefront of the country’s mind, were soon discounted. It was soon concluded that a likely source of the anthrax, which was of the Ames strain, had been maintained by the US Army Medical Research Institute of Infectious Diseases (USAMRIID). Suspicion fell on Dr Bruce Ivins, who had been a researcher at the facility. Whilst in this position, Ivins had created and maintained this particular spore-batch, suspected to have been the batch used in the anthrax attack. With suspicions supported by an array of incriminating circumstantial evidence, investigators called upon a team of scientific experts to establish whether there was a link between Ivins’ own anthrax and the mailed anthrax.

anth2

Traditional forensic techniques were used in the examination of the spore powder and the letters and envelopes, including fingerprinting, and hair and fibre analysis, though this did not lead to any major breakthrough. A suite of analytical techniques was employed to ascertain various facts regarding the anthrax. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to identify the size, shape and quality of the anthrax spores, as well as provide a profile of the chemical elements within the spores. SEM and TEM are microscopy techniques which employ a focused beam of electrons which interacts with the atoms of the sample, allowing it to be visualised. They can be coupled with energy-dispersive X-ray (EDX) spectroscopy to provide elemental analysis. The physical and chemical characteristics of the spores allowed investigators to presume that the anthrax was not weapons-grade, but it was of a concentration and quality similar to that used in bio-defence research.

Inductively coupled plasma optical emission spectroscopy (ICP-OES), a technique based on the emission of photons from substances, was used to provide further details of the elemental composition of the spore powder. Furthermore, gas chromatography mass spectrometry (GC-MS) was employed to characterise the spores. Experts at the Center for Accelerator Mass Spectrometry (CAMS) were called upon to analyse the anthrax spores and establish their relative age. Accelerator mass spectrometry turns a sample, which has been converted into solid graphite by the analyst beforehand, into ions and accelerates these ions to high kinetic energies before conducting mass analysis to detect C14 (and potentially other isotopes depending on the work) to estimate the age of a sample. The analyses carried out on the samples in this instance determined that the mailed anthrax has been produced within 12 months of the attack, narrowing down the possible sources and suspects.

But perhaps the biggest breakthrough in the case came from a newly developed DNA fingerprinting technique which allowed investigators to conclude that the blend of anthrax spores created by Ivins in the lab was identical to that used in the attack, though how unique this “genetic signature” was has been somewhat debated. The US Justice Department later concluded that Ivins was solely responsible for the preparation and mailing of the deadly spores, claiming that he believed the scare would resurrect his anthrax vaccine program. Ivins later died from an overdose, deemed to be a suicide.

The case of Dr Ivins and the anthrax letters is a great example of how different analytical techniques can be drawn together to work in perfect harmony, utilising their individual powers to find out everything there is to know about a sample. In this case the array of techniques used allowed investigators to discover what the spores looked like and what they were composed of, their concentration and quality, and even how old they were. Armed with this information, investigators could home in on the source of the anthrax spores and the man behind the attack.

References

Centre for Infectious Disease Research and Policy. FBI says it easily replicated anthrax used in attacks.

US Department of Justice (2010). Amerithrax Investigative Summary. Darby, PA: DIANE Publishing.

Washington Post. FBI investigation of 2001 anthrax attacks concluded; U.S. releases details. [online] Available: http://www.washingtonpost.com/wp-dyn/content/article/2010/02/19/AR2010021902369.html

Forensic Failures: DNA Evidence and the Phantom of Heilbronn

Forensic Failures: DNA Evidence and the Phantom of Heilbronn

In 1993, the existence of a brutal murderer came to light when an elderly woman was strangled with a length of wire and left for dead in Germany, the perpetrator leaving behind nothing more than DNA on a teacup. The criminal did not stop there, and over the next decade and a half a sequence of crimes ensued, ranging from murders to car thefts to household burglaries. What did this string of ruthless attacks and petty crime have in common? Very little, with the exception of DNA from one individual recovered at each scene. A total of around 40 crime scenes all pointed to the same culprit.

Analysis of the DNA revealed the serial killer to be, somewhat surprisingly, a woman. Analysis of mitochondrial DNA indicated that the sinister suspect was most likely of Eastern European or Russian descent, narrowing down the list of suspects but not nearly enough. A bizarre picture of this woman began to form. The notorious killer became known as the Phantom of Heilbronn, a fiendish criminal with a 300,000 euro reward on her head. Also known as the Woman Without a Face, Germany’s most dangerous woman was responsible for the murder of half a dozen people… but also had a soft spot for theft?

dna

It sounds like a baffling crime fiction novel in which the killer is never brought to justice, slipping through the net and always staying one step ahead of the perplexed police. However there is one slightly twist to this tale… the Phantom of Heilbronn was indeed never found, and a few years ago German police made a somewhat embarrassing confession… they had been pursuing a non-existent serial killer for 16 years. The Phantom of Heilbronn did not exist.

But how could this be? A series of vicious crimes and evidence of a single perpetrator at every scene, it seems like a reasonable assumption that this was the work of the same person. And this is just what investigators believed for a rather long time.

However suspicions were raised during the investigation of a person who had died in a fire, at which point the DNA of the “serial killer” was found on the body when attempting to identify the victim. The victim transpired to be a male asylum-seeker, so why had female DNA been recovered from the scene? This was bizarre enough, but even more so when subsequent tests (presumably using different swabs) failed to find the DNA again.

It soon came to light that police had been following the wrong scent, and suspicion soon fell elsewhere… cotton swabs. It eventually emerged that the DNA recovered from all of these crime scenes belonged to none other than an unsuspecting woman working in a swab factory in Bavaria, a factory which happened to have numerous Eastern European women on its staff (at least part of the serial killer profile was right). And so the mystery of the Phantom of Heilbronn was solved. Investigators had been collecting samples from numerous crime scenes using cotton swabs inadvertently contaminated with the DNA of a slightly careless factory worker. No doubt there were some red faces the day this little tidbit of information came to light!

So how could something quite so farcical occur in the first place? Let’s review the facts. We have a female serial killer, unusual in itself (women account for about 9% of serial killers, according to research carried out by Radford University), but not unheard of so no suspicions were raised there. The crimes appeared to cover all manner of sins, from murder to drugs to burglaries. Perhaps a little unusual, but theories began floating that the suspect was a drug addict or homeless person who would stop at nothing to steal some quick cash to get their next fix. This criminal’s DNA was found in all sorts of bizarre places, including on the remains of a cookie and on a toy gun. The wrongdoings spread over a decade and across three different countries, never leaving behind anything else that might point to the identity of the culprit. One would assume this took the homeless woman theory out of play – there are probably not many people living on the streets who have the funds to hop from country to country on a crime spree. In short, this phantom was one busy woman who liked to travel and mix up her wrongdoings!

Sounds somewhat ridiculous in hindsight. So why did it never occur to anyone that perhaps something else was afoot? After spending so many years tracking this villain, perhaps the concept of her not actually existing was impossible to comprehend. Investigators had spent years trying to get inside this woman’s head and figure out her motives, and the evidence was there to support their (slightly farfetched) theories. If nothing else, this highlights the dangers of being too committed to one line of evidence. It’s a very real problem for investigators and scientists. Once a hypothesis has been developed and a person genuinely believes in this theory, it is very easy to ignore subtle (or not so subtle!) indicators that the precious theory might be wrong. Suddenly, all evidence and results can be twisted to fit the theory, whether ludicrous or not. Not great scientific analysis, but it happens.

The case shed light on the fallacies of forensic evidence, even those which we tend to place great faith in. DNA evidence is perhaps viewed as one of the more reliable practices in forensic science, provided the appropriate procedures are followed (did these investigators even run control samples?). But at the time DNA analysis was something of a forensic holy grail, certainly not a technique which would draw investigators down the wrong path for over a decade. Yet from this incident, and many others since then, it is clear that even the best of techniques and practices must be accompanied with sound logic and an open mind.

As embarrassing (if slightly amusing) as this case might be, it highlighted some very real issues. To be sent back to some laboratory basics – know your equipment, always run controls and follow the results, not your hypothesis!

Putting aside the shame-faced investigators, the millions spent, the dozens of investigations affected and the police hours wasted, it at least makes for an interesting cautionary tale to tell budding forensic scientists for years to come.

References

BBC News. ‘DNA bungle’ haunts German police. [online][Accessed 23 Mar 2015] Available: http://news.bbc.co.uk/1/hi/world/europe/7966641.stm

The Guardian. DNA analysis: far from an open-and-shut case. [online][Accessed 23 Mar 2015] Available: http://www.theguardian.com/science/2012/oct/14/vaughan-bell-on-science-forensics

Time. Germany’s Phantom Serial Killer: A DNA Blunder. [online][Accessed 23 Mar 2015] Available: http://content.time.com/time/world/article/0,8599,1888126,00.html