Month: March 2015

The Challenges of Forensic Air Crash Investigations
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The Challenges of Forensic Air Crash Investigations

The subject of aircraft crashes has unfortunately dominated the media headlines at numerous points over the past couple of years, ranging from malicious attacks, such as the plane shot down over Ukraine in July 2014, to still somewhat unresolved incidents, in particular the missing Malaysia MH370 flight that disappeared in the ocean in March that same year.

As one would expect, the investigation that ensues is often gruelling, time-consuming and expensive, requiring the expertise from a variety of fields and often collaboration between countries in accordance with International Civil Aviation Organization guidelines. The investigation of any incident scene, whether criminal, accidental or natural, will be accompanied by its own set of difficulties and problems. The forensic investigation of a plane crash is certainly no exception.

The Investigation

The discovery of an incident involving an aircraft typically comes to light when air traffic control loses communication with the plane, particularly if the pilots had previously made a distress call. The exact location of the crash site may or may not be immediately obvious. Either way, a number of teams will be instantly gathered to begin the investigation, with the earlier hours of the incident being the most crucial.

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As much information about the aircraft will be gathered as possible, particularly pertaining to its maintenance history and if there had been any signs of a potential fault, as well as details of the crew. Weather information will be collected and scrutinised for any possible occurrences that may have placed the aircraft in difficulty. If there were any witnesses to the incident, such as people in the area in which the plane crashed, they may be able to provide beneficial information regarding how the plane looked prior to crashing.

The investigation of the scene itself will involve a tremendous amount of documentation, as with any crime or accident scene, though made immensely more difficult by the likely sheer size of the area under examination. Examination of the wreckage itself may, in theory, aid in establishing the cause of an aircraft incident, such as through examination of a faulty component or the discovery of debris that would suggest a malicious attack. For instance, in the investigation of the shot-down MH17 plane, there was evidence on the outside of the aircraft indicating something trying to get into the plane (in this case the projectile used to destroy it), as oppose to anything originating inside the aircraft. Unfortunately the nature of such incidents are often so catastrophic that even locating such remains are a challenge, as more often than not the debris is strewn over a vast area. Even if components are retrieved, they may have been destroyed by the crash or fire, reducing their value as evidence.

Crash Location

The ease of the investigation of the wreckage and recovery of bodies is largely determined by the site of the crash. When an incident occurs at sea, simply locating the wreckage is the first greatest challenge, and in many cases the plane and thus the people on board are never found. If the wreckage is located, the process of recovering victims and airplane components from the bottom of the ocean is by no means an easy task. This can often be a dangerous process involving highly-skilled divers and specialist equipment, such as inflatable balloons which can be attached to pieces of the aircraft to draw them to the surface for collection.

Should the aircraft strike land, depending on the nature of the crash the wreckage will most likely to scattered across a vast area, making simply identifying and controlling the entire incident scene a great difficulty, let alone effectively investigating it. In the case of the March 2015 Germanwings crash, the incident occurred in the Alps, a mountainous area making scene investigation especially troublesome and dangerous for those involved.

Aviation incidents can occur over any country, which in itself can be problematic in terms of managing the investigation. As in the case of the aircraft shot down over Ukraine in 2014, pieces of the wreckage remained in dangerous areas riddled with war and fighting. These factors can make the vital immediate access to the crash site difficult if not impossible, greatly hindering an investigation. There may be further complications brought about by explosions and fires caused when the aircraft crashes, making accessing the wreckage more difficult as well as potentially compromising already damaged evidence.

Data Recorders

When an aviation incident takes place, one of the primary goals of investigators is finding a device known as the black box (though these are actually bright orange in colour). Modern aircraft are now equipped with a number of data recording devices, well-built components designed to record as much data as possible relevant to the aircraft prior to and during the incident and ideally survive crashes and fires. The black box is a small device generally bolted to the aircraft’s tail so as to prevent severe damage in the event of a head-on crash. bb

These devices are also equipped with an underwater locator beacon, which is activated if the recorder comes into contact with water. This allows investigators to detect ‘pings’ emitted by the device so that the black box can be located. However the device can of course only function for a limited amount of time, typically for around 30 days before battery life is exhausted, so investigators are working against the clock to locate this vital piece of equipment.

The flight data recorder is a device used to record certain operating parameters from the aircraft’s system, the examination of which may be able to indicate if there were any major faults with the aircraft. This can record a range of details including altitude, time, direction, and airspeed, as well as the movement of certain aircraft components, auto-pilot details and fuel levels. The cockpit voice recorder is a unit which typically records sound from microphones worn by the pilot and the co-pilot as well as from the cockpit area. If this device can be recovered intact (or at least intact enough to retrieve data files), documentation of what was audibly occurring in the cockpit prior to and during the incident can be invaluable, particularly if the pilots were unable to communication with air traffic control at the time.

Victim Identification

Looking at the catastrophic scenes caused by some aircraft crashes, it is of no surprise that identification of passengers and crew can be an difficult task. Locating the bodies of victims can be a gruelling enough mission, particularly if the incident occurred at sea or over a poorly-accessible area, such as the recent incident over the Alps. When victims are located, the bodies may be damaged beyond recognition by the crash itself, fire, water, or even decomposition if recovery of bodies was delayed. In these instances specialised forensic experts may be required to carry out DNA analysis or examination of dental records, guided by the details known about the victims from flight manifests and the assistance of family members.

Lessons Learned

Despite a number of recent high-profile plane crashes, aviation remains one of the safest forms of transport, in part down to the strict operating and safety procedures adhered to, many of which were developed following aviation incidents and investigations. If investigators can at least in part deduce what happened to cause an incident, steps can be taken to prevent reoccurrence and make flying safer.

References

Anthiniotis, N et al. Scientific analysis methods applied to an investigation of an aircraft accident. Eng Fail Anal. 17 (2010), pp 83-91.

BBC News. Malaysia plane; Why black boxes can’t always provide the answers. [online] Available: http://www.bbc.co.uk/news/magazine-26721975

Robson Forensic. Airplane Accident Investigations. [online] Available: http://www.robsonforensic.com/practice-areas/airplane-accident-investigation-expert

Bugs, Bleach and Bodies
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Bugs, Bleach and Bodies

Following on from my last post focusing on forensic entomologist Dr Zak, it seemed apt to carry on with a recent piece of forensic entomology research I came across.

In forensic entomology, post-mortem interval (the time since the victim’s death) is typically estimated based on the types of insect present at the scene and, most importantly, their stage of development. It is probably of no surprise that flies (Order: Diptera) play a big part in insect colonisation of a cadaver, thus have been subject to a lot of research in forensic entomology. The life cycles of certain flies are relatively well known in terms of the different stages of development and when those stages are likely to be reached.

fly2The lifecycle of a fly consists of a number of stages: egg, 1st instar, 2nd instar, 3rd instar, pre-pupa, pupa, and finally the adult fly (instar refers to stages of moulting as larvae). The time taken to reach each phase can vary between species. And there are of course factors which affect these development times, some that have been greatly studied, including environmental temperature, sun exposure, food availability, and even drugs taken by the deceased prior to death.

Now researchers are branching out into the study of other affecting factors, in this case typical household products. It isn’t uncommon for certain products to be spilled or in some other way present at the scene of a death (whether criminal or otherwise). Maybe a victim was smothered in acid in vain attempts to dispose of the body (good luck with that one) or perhaps the deceased happened to have slathered on some insect repellent immediately before his or her untimely death. Regardless, the ways in which chemicals appear at a death scene are plentiful, and they need to be taken into account if we’re relying on a somewhat environmentally-dependent factor to determine the post-mortem interval.

Enter researchers at the University of Lille Nord de France.

These guys and girls aimed to figure out how some common chemicals might affect the development of a particular species of common fly (in this case Lucilia sericata, the green bottle fly) by allowing the first instar larvae to feast on beef liver laced with different chemicals – in particular bleach, perfume, hydrochloric acid, caustic soda, insecticide, mosquito repellent, and gasoline. Specimens were subjected to either low concentrations of the chemicals (supposedly the equivalent to a realistic quantity being splashed on or otherwise applied to the body) or high concentrations. The development of the different groups of Lucilia sericata were then studied, allowing researchers to establish whether the chemicals present delayed, accelerated or had no effect on larval development, as well as possible effects on insect size, survival rate and sex ratio.

The results were interesting even if they were not wildly significant (ignoring the chemicals which just outright killed all subjects, not making them terribly useful post-mortem indicators). Low concentrations of mosquito repellent and caustic soda extended the development time of the larvae (361 hours and 352 hours respectively, in comparison to the control of 333 hours), as did high concentrations of perfume (342 hours). These figures I’ve listed are hours taken to reach adulthood, the mean values being used. At first glance these may not seem like such large differences, but what a difference a day makes when trying to pinpoint time since death (though the confidence interval typically used by entomologists is about 25 hours). There were also certain size variations noticed between adults fed on different sources, though this was not a particular focus of the study so no conclusions can really be made. The research also looked at survival rates and sex ratio, but I will skim over this (with the exception of pointing out that perfumed meat resulted in the survival of more females over males – we ladies do enjoy a good perfume!). Despite the limitations of the work and the relatively small differences caused, differences were observed, which suggests this path of research could be a fascinating and relevant one.

Realistically this was a pretty limited study, looking at a single species of laboratory-reared larvae and examining a small handful of household products, but the results are interesting nonetheless, indicating the impact of household chemicals on necrophagous fly development. We know conclusively that certain factors can have a renowned effect on the development of insects, thus affecting what we know about figuring out time since death. However taking into account what else might be on the victim’s body is something that may be overlooked, or at least not considered by the lay person perhaps.

So next time you’re slapping on some repellent to keep the mosquitos at bay, give a thought to the forensic entomologist whose day you might be making a little more tricky.

References

Aubernon, C et al. In vitro effects of household products on Calliphoridae larvae development: implication for forensic entomology. J Forensic Sci. 60 (2015), pp 226-232.

 

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Scientist Special: Zakaria Erzinçlioglu
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Scientist Special: Zakaria Erzinçlioglu

From fly-infested corpses to forensic politics, self-titled “maggotologist” Zakaria Erzinçlioglu pioneered forensic entomology in Britain and fought for a better criminal justice system.

Perhaps Britain’s leading forensic entomologist, Zakaria Erzinçlioglu dedicated most of his career to the application of his extensive knowledge of insects to legal investigations. Born in Hungary in 1951, he went on the live in Egypt, the Sudan and finally England, where he carried out much of his work. Most commonly referred to as Dr Zak (I will take a wild guess and assume his colleagues and students struggled with his surname!), he fell into the fascinating world of forensic science somewhat incidentally. As an entomologist with a great interest in the transmission of diseases by insects, in the early 1970s he soon found himself being called upon by the police to offer expert advice on insect evidence. As more and more requests for advice such as this were made, Dr Zak soon realised that this fascinating branch of entomology was where his career would take him.

After dedicating his doctorate to the study of blowfly development, he moved around the country working for a number of institutions, working within the Zoology department at the University of Cambridge, carrying out forensic entomological research funded by the Home Office, and acting as director of Durham University’s Forensic Science Research Centre.

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He contributed his expertise to a range of infamous criminal investigations, including the investigation of a notorious paedophile ring responsible for the death of a 14-year old boy, the trial of serial rapist and murderer Robert Black, and the case of lecturer-turned-murderer Dr Samson Perera. In the investigation involving Dr Perera, a dental biologist suspected of murdering his adopted daughter Nilanthie, Dr Zak was called upon when a number of bones were found in the lecturer’s home and laboratory. Whereas Perera insisted the bones were specimens for medical research (as dental biologist of course often require femurs and spinal cords for their work…), Erzinçlioglu was able to conclude that the bones were recent and had been dismembered, all through the examination of a specific fly still present on some of the samples. Erzinçlioglu’s expertise helped put to rest scores of criminal cases, however his contribution to the field of forensics was not just entomology-based, but also somewhat political.

Dr Zak developed a certain discontentment with the provision of forensic science services in Britain, a disapproval which he did not keep to himself. He called for a single statutory body of forensic science which answered solely to the judiciary, not to be hired by prosecution or defence, allowing the forensic expert to act as an entirely unbiased expert witness. In an article published in the Contemporary Review in 1998, Erzinçlioglu stressed that any forensic expert hired by either side of the adversarial system used in the UK would be “presented with a line that he is required to support”, encouraging the scientist to protect his or her reputation by offering a good service to the employer, thus jeopardising their ability to be an impartial expert. His determination to raise standards in forensic science were relentless, and he even later went on to offer his expertise to cases of miscarriages of justice, charging no fee and simply wishing to aid those who required his expertise.

He went on to publish a number of papers along with “Maggots, Murder and Men”, a book which provided a fascinating introduction to the science of forensic entomology and a range of case studies. He had numerous other publications in progress, but Dr Zak sadly passed away at the age of 50 on 26th September 2002.

References

Erzinçlioglu, Z (2013). Maggots, Murder, and Men: Memories and Reflections of a Forensic Entomologist. NYC: St. Martin’s Press. 12.

Erzilnclioglu, Z. Reform of forensic science provision. Some basic questions. Science & Justice, 40(2000), pp. 147-149.

Innocent. Science and the law: a cause for concern. [online][Accessed 12 Mar 2015] Available: http://www.innocent.org.uk/misc/cr_erzingclioglu_fss.html

The Telegraph. Zakaria Erzinclioglu. [online][Accessed 12 Mar 2015] Available: http://www.telegraph.co.uk/news/obituaries/1412780/Zakaria-Erzinclioglu.html

Facing the Facts on DNA Phenotyping
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Facing the Facts on DNA Phenotyping

Last week a somewhat fascinating article was published by the New York Times discussing forensic DNA phenotyping, a new(ish) technique that allows for (as popular media would say) a person’s face to be reconstructed from only their DNA. It sounds almost science fiction-esque doesn’t it?

Media interest in the topic appears to have been resurrected over the last couple of months by the use of DNA phenotyping by law enforcement officers in Colombia, South Carolina, investigating the unsolved 2011 murder of Candra Alston and her daughter Malaysia Boykin. Investigators hired the services of an independent company to carry out DNA phenotyping on DNA recovered from the crime scene years before, resulting in the production of the apparent face of the suspect.

This is not novel, ground-breaking work. In fact the whole concept of this technique has been floating around for a few years now (though this was presumably the first case in which a face reconstructed solely from DNA was presented to the general public).

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But just what actually is DNA phenotyping? As you may or may not recall, a phenotype is a physical characteristics which is the result of genetics, for instance the colour of one’s hair, eyes or skin. DNA phenotyping essentially attempts to determine physical traits such as these using only genetic material. This is based on the idea that certain genes are contributors to particular characteristics. Theoretically, this could be such a powerful tool for investigators, forensic, historical and medical investigators alike. Imagine a piece of software which is simply fed a DNA profile and spits out the face of your perpetrator (viewing it in a very black box manner of course). A face which could then be compared to existing mugshots of criminals or circulated to trigger recognition. Or the reconstructed face of a member of some ancient civilization. The possible applications are exciting and plentiful.

But it is of little surprise that, since the publication of this work over the last few years, numerous accounts emerged in the media blowing the results way out of proportion. If one were to Google DNA phenotyping, it is easy to believe it is a well-established technique often used in legal investigations around the world. In reality, this is a technique that is not permitted in court and in fact some countries have outright banned the use of DNA phenotyping (perhaps more for ethical purposes than concerns over accuracy). A research team at Penn State University in the US, led by Peter Claes and Mark Shriver, has been conducting research into this field of work. Despite the promising results published by the group, it has been made clear that the work so far provides an “analytical framework” but considerable further research is needed. Before any claims are made that scientists can reliably re-create a face from DNA, one must pay attention to the current lack of knowledge, inaccuracies and issues linked with DNA phenotyping, unfortunately often ignored by the media.

There are obviously clear ethical concerns associated with such techniques. Unsurprisingly, concerns over the possibility of racial profiling occurring have been raised. The images produced by DNA phenotyping methods have been referred to as being “generic” and could easily draw investigators down the wrong path as they focus solely on a particular physical characteristic suggested by this method. But on the other hand, could an eyewitness account, which are often famed for being ripe with inaccuracies, not also lead to such problems, should the eyewitness state the race of the person they saw?

Ethics aside, the accuracy of the technique is no doubt at the forefront of most people’s mind. Undoubtedly the face that is reconstructed can only ever be a kind of estimation based on the information available, being unable to take into account a whole array of factors that go beyond DNA. Dyed hair, hairstyle, facial piercings, tattoos, accessories, scars, even down to a person’s characteristic facial expressions which can wildly change the appearance of a face. Many genes are known to contribute to the development of a person’s face and the appearance of certain characteristics, and these genes can be targeted in this kind of work. But it does not take an expert in genetics to conclude that there are equally many genes that may contribute to appearance that we do not know about. So how accurate can this technique really be (at this point in time anyway)?  And regardless of the actual accuracies (or inaccuracies, if you wish) of this technique, somewhat equally as important is how people actually perceive it. Anyone with the slightest interest in forensic science is no doubt aware of the so-called “CSI effect”, which has raised concerns over how lay people perceive scientific (or sometimes even unscientific) techniques. Is it plausible that, should DNA phenotyping be accepted into a courtroom, members of the jury will see “DNA” and assume it must be just as trustworthy as established DNA profiling techniques?

Despite the possible benefits of this technique, there is ultimately currently no way only the DNA of an individual can be used to reconstruct their face.

Thus this is a technique still under research, not yet developed enough to actually be used in legal investigations. And yet, in the United States at least, various independent companies are offering DNA phenotyping services. The law enforcement agency referred to at the beginning of this post in fact used one of these services. The results of these companies list a range of biological and physical attributes, including sex, skin colour, eye colour, hair colour, probable ancestry, and even if the suspect is likely to have freckles! It has even been suggested that genetic analysis could be a predictor of a person’s age. There is an array of factors that can affect a person’s appearance that do not necessarily have anything to do with their genetics, and a person’s DNA can in no way account for this.

These facts by no means aim to take anything away from the technique. DNA phenotyping undoubtedly can unlock entirely new routes of investigation for law enforcement officers, and it has been successfully used in a number of cases. Even if its use would not currently be accepted as evidence in court, it may still provide law enforcement with new investigative leads if other lines of inquiry have been exhausted.

Although the concept of DNA phenotyping emerged years ago and made slow progress, in the last couple of years research and interest appear to have boomed. It is a fascinating topic with huge potential, but it is ripe with practical and ethical concerns that will no doubt bring about some very intriguing debates. I am sure we will be hearing much more about this in the coming years.

References

Claes, P. Shriver, M D. Establishing a multidisciplinary context for modelling 3D facial shape from DNA. PLos Genet. 10 (2014).

Claes, P. Hill, H. Shriver, M D. Toward DNA-based facial composites: preliminary results and validation. Forensic Sci Int Gen. 13 (2014), pp. 208-216.

New Scientist. Genetic mugshot recreates faces from nothing but DNA. [online][Accessed 02 Mar 2015] Available: http://www.newscientist.com/article/mg22129613.600-genetic-mugshot-recreates-faces-from-nothing-but-dna.html#.VPSBpvmsV8E

The New York Times. Building a Face, and a Case, on DNA. [online][Accessed 02 Mar 2015] Available: http://www.nytimes.com/2015/02/24/science/building-face-and-a-case-on-dna.html?ref=science