Forensic Failures: Three Men, Three Hairs, Three Wrongful Convictions

Forensic Failures: Three Men, Three Hairs, Three Wrongful Convictions

In the summer of 1978, 63-year-old taxi driver John McCormick was robbed and shot on his own doorstep in his Washington, D.C home. His wife, roused from sleep by the cries of her husband pleading for his life, ran to his aid to briefly glimpse the gunman, a man with a stocking mask shielding his face. McCormick died as a result of the attack, shot by a .32 calibre handgun. A police officer and his dog later found the stocking mask nearby, and from this a number of hairs were recovered.

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Santae Tribble (Source: The Innocence Project)

Suspicion soon fell on 17-year-old Santae Tribble, implicated by an informant, Bobby Jean Phillips, who claimed Tribble had recently sold a .32 calibre handgun to her roommate. A weapon that, incidentally, was never successfully linked to the gun used to kill McCormick. Tribble was pulled in for questioning. Hairs recovered from the stocking used by the killer were compared to samples collected from the suspect and, according to an FBI analyst, “matched in all microscopic characteristics”. At trial, the prosecution went on to declare that there was perhaps a “one chance in ten million” that the hair belonged to someone else. Seemingly compelling “statistics” and apparently sufficient in helping the jury reach a verdict. Despite having testified that he was in Maryland at the time of the attack, an alibi supported by half a dozen witnesses, in January 1980 Santae Tribble was found guilty of murder and sentenced to 20 years to life in prison.

Meanwhile, as Tribble was adjusting to prison life, another man’s world was about to be turned upside down thanks to a single hair. In February 1981, a 27-year-old woman was bound, raped and robbed in her apartment, briefly glimpsing her attacker in the dim light. The distraught victim helped police construct a composite sketch of her attacker; a young, cleanly shaven African American man. Unfortunately for 18-year-old Kirk Odom in the following weeks, a passing police officer decided that Odom resembled the composite sketch, passing on his suspicions to the detective leading the case. As a result of this Odom was presented to the victim as part of a somewhat dubiously organised line-up, with Odom standing on a box in order to match the height of the other men in the line-up, who were actually police officers. The victim identified Odom as her attacker.

kirk

Kirk Odom (Source: The Innocence Project)

During the trial, FBI Agent Myron Scholberg testified that the “Negroid hair” found on the victim’s nightgown was microscopically similar to a hair sample taken from Odom, “meaning the samples were indistinguishable”. He declared this to be “a very rare phenomenon”, and in the thousands of occurrences in which he had compared hair samples, on only eight or ten occasions had he failed to distinguish the hairs of two different people. Understandably, this implied a very substantial likelihood that the hair did in fact belong to Odom, and after only a few hours deliberating he was found guilty and sentenced to 20 to 66 years in prison.

In June that same year, a worryingly similar scenario ensued after 21-year-old student Catherine Schilling was found raped and murdered in Rock Creek Park, Washington. She was discovered naked and shot five times in the head. A somewhat questionable police informant, Gerald Mack Smith, relayed to police that he had been drinking in the park with a man who had admitted to killing the woman after attempting to rob her. That man was allegedly Donald Eugene Gates. It is worth noting that, not only was Smith paid by police for his information, but at the time he had two prior felony convictions and had recently been indicted for a third felony, which was conveniently dismissed after he aided the police in incriminating Gates. This information was not relayed to the defence team.

Donald Gates - Washington Post

Donald Gates (Source: The Washington Post)

So Donald Gates, aged 30 at the time, was arrested and charged with murder, not only based on the testimony of Gerald Smith, but also largely on the comparison of hair samples. FBI forensic analyst Michael Malone testified in this case, establishing that hairs recovered from the scene were “microscopically indistinguishable” from a hair sample taken from Gates. The expert witness claimed that in his many years of hair comparison work, there were perhaps two in ten thousand cases where hairs from two people could not be distinguished. Once again, seemingly convincing statistics to a lay jury. In September 1982, Gates was found guilty and sentenced to 20 years to life in prison.

Forensic Hair analysis

What do these three cases have in common? All men were wrongfully convicted for crimes they did not commit. And all convictions were largely based on flawed expert witness testimony relating to hair analysis.

The potential evidential value of human hair stems from its prevalence at crime scenes and the ease with which it can be imperceptibly transferred. It is fairly resilient and can persist at a crime scene for many years after the incident took place, all-in-all making hair a potentially vital piece of evidence well worthy of examination.

What does this examination involve? Forensic hair analysis is a type of ‘comparison analysis’ – that is an examination that is typically based on individual or class characteristics rather than incorporating numerical analyses. It generally involves the study of microscopic characteristics relating to whether the hair is human or animal, the colour, length, diameter, likely racial group, area of bodily origin, phase of growth, and so on.

Hair 2 - Wikimedia

Microscope image of hair sample

The examination may include an even closer scrutiny of patterns and intricacies along the shaft of the hair. The human hair can be described as being composed of three distinct regions: the medulla, the cortex and the cuticle. The medulla refers to the inner core of the shaft, the cortex as the surrounding material, and the cuticle the outermost protective layer. The cuticle is composed of a scale-like complexion, which can be particularly beneficial in distinguishing between animal hairs and human hairs. Cuticle characteristics will be noted in the comparison of hair samples, particularly the thickness of the cuticle, the colour, and the general shape of the “scales”. The cortex is the portion of the hair containing pigment granules which give hair its colour, obviously vital in the comparison of different samples. These pigment granules vary between racial groups, thus are pivotal in establishing whether a hair is likely Caucasian or Negroid in origin, for instance. The medulla in the centre of the hair shaft will also be scrutinised to determine whether the core is continuous, interrupted, fragmentary or absent.

This is a limited list of the features focussed on during forensic hair analysis. In reality there is a myriad of other features, both natural such as those above and artificial such as dyeing and damage, that can be used in studying the similarities and differences between hair samples. So it would seem there is an abundance of information with which to reach a conclusion. However the problem lies in that these are all class characteristics whose description is based on the individual analyst’s subjective observations.

Obviously the ideal situation would involve some form of statistical analysis to determine the reliability of comparisons, but the vast number of variable factors in hair comparison makes statistical analysis tremendously complex if not impossible. This in itself does not render such analyses worthless in criminal proceedings, provided accurate testimony is given and caveats made clear. In the aforementioned cases, and potentially others, expert witness testimony strongly implied that exact matches between hair samples had been made, and in some instances fictitious statistics were even expressed to the jury. When such evidence is presented by a seemingly distinguished scientist who may be an expert in their field, naturally members of a lay jury with little or no knowledge of the topic are unlikely to challenge this evidence. The FBI’s own guidelines on forensic hair analysis conclude that “the science of microscopic hair examination can never result in an identification” but can “provide a strong basis for an association”, but unfortunately this ethos was not always carried into the courtroom.

Collectively, Tribble, Odom and Gates served nearly 80 years in prison. All three men were eventually released and exonerated by DNA testing and the actual perpetrators identified. However by the time this was achieved, perpetrators had passed away or were able to evade conviction due to expiration of the statute of limitations. The wrongfully convicted men were awarded millions of dollars in compensation, but hardly a prize worthy of losing so many years.

As a result of these incidents, and numerous others, ongoing investigations are aiming to identify further miscarriages of justice in the United States, initially largely powered by the Innocence Project, a non-profit organisation which aims to exonerate wrongly convicted people through DNA testing. Furthermore, efforts are underway to focus on how forensic science standards can be strengthened to avoid future errors, particularly in relation to forensic ‘comparison analyses’.

 

References

Federal Bureau of Investigation. Forensic hair comparison: background information for interpretation. [online] Available: https://www.fbi.gov/about-us/lab/forensic-science-communications/fsc/april2009/review/2009_04_review02.htm

Innocence Project. Donald Eugene Gates. [online] Available: http://www.innocenceproject.org/cases-false-imprisonment/donald-eugene-gates

National Registry of Exonerations. Kirk Odom. [online] Available: https://www.law.umich.edu/special/exoneration/pages/casedetail.aspx?caseid=3943

Taupin, J. M. Forensic hair morphology comparison – a dying art or junk science? Sci & Justice. 44 (2004), pp. 95-100.

The Washington Post. Santae Tribble cleared in 1978 murder based on DNA hair test. [online] Available: https://www.washingtonpost.com/local/crime/dc-judge-exonerates-santae-tribble-of-1978-murder-based-on-dna-hair-test/2012/12/14/da71ce00-d02c-11e1-b630-190a983a2e0d_story.html

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Silencing Spies & Secrets: Radioactive Murder

Silencing Spies & Secrets: Radioactive Murder

Last week the news was awash with a chilling yet familiar photo – the infamous shot of 43-year-old Alexander Litvinenko dying in his hospital bed, his body wrecked by radiation poisoning.

In 2006, the former Russian spy died in London as a result of polonium-210 poisoning, believed to have been ingested via a seemingly innocuous cup of tea. Having fled from his previous life as an officer with Russia’s Federal Security Service (the KGB’s successor), Litvinenko soon became something of an enemy to the Russian government. Publishing a shocking book claiming Russia’s secret service was behind a terrorist attack in Moscow, accompanied by frequent public criticisms of the Kremlin and President Vladimir Putin, it is of no surprise that Russian authorities are suspected of being behind Litvinenko’s ruthless death.

So one fateful night a few weeks before his life ended, the former spy thought nothing of meeting with Andrei Lugovoi and Dmitry Kovtun, both with a history in the KGB, in Millennium Hotel in London to indulge in a pot of tea. But just hours after this innocent beverage, Litvinenko fell terribly ill, passing away 22 days later. His death was later attributed to poisoning by polonium-210.

Unfortunately this is not an unfamiliar story.

The politically well-connected Roman Tsepov succumbed to a similar fate in 2004, falling mysteriously ill and displaying the same symptoms that would plague Litvinenko two years later. His doctor at the time described his illness as “a poisoning without a poison… as if his immune system was switched off”. Although the motive behind his possible assassination was never established, a post-mortem concluded that he had been poisoned by some kind of radioactive material present in a concentration one million times greater than the normal amount.

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Alexander Litvinenko (Source: The Independent)

 

Spookingly similarly, Yuri Shchekochikhin a Russian journalist known for writing on the controversial topics of organised crime and government corruption, play victim in a sadly comparable story. Due to fly to the US to meet with FBI investigators in July 2003, Shchekochikhin fell suddenly ill and died. The already suspicious circumstances were heightened by the secrecy surrounding his medical records, and Litvinenko himself later claimed that this man’s death was the result of assassination ordered by government officials, apparently unaware that he would meet the same fate.

A decade prior to this, in 1993, packing company director Vladimir Kaplun is believed to have been the first person to be murdered using radioactive material, in this instance planted in his chair, causing him to eventually die from prolonged exposure to radiation. Although never proven, the use of radioactive materials as a means of murder has been suggested in all of these cases. But just what is a radioactive substance, and what are its effects on the human body?

Radioactive Substances

We all know that everything in the world is composed of atoms – little bundles of sub-atomic particles which group together to produce substances with a whole range of characteristics and potential uses. Some of these atoms are unstable, spitting out energy in the form of radiation from the nucleus as it decays to a more stable state, and it is this type of atom that is referred to as being radioactive.

There are various types of radioactive material, categorised depending on the particles they emit whilst decaying. Ionising radiation is typically grouped as alpha, beta or gamma sources (X-rays and parts of the ultraviolet spectrum are also ionising, but we won’t discuss those here). Alpha particles consist of two protons and two neutrons (essentially a helium atom). Of the types of radiation discussed, alpha particles are the least penetrating, being halted in their tracks by just a few pieces of paper or certainly human skin. For this reason, radioactive material emitting alpha radiation is relatively safe to handle (provided you don’t eat it – then it’s a different story). Beta radiation has a greater penetrating power, having the ability to pass through a few metres of air and a few millimetres of tissue, potentially resulting in burns to the skin and eyes if contact is made. Finally, gamma radiation poses the greatest risk, being able to penetrate skin and clothing to any depth, only stopped by a sufficient amount of lead or concrete.

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Alexander Litvinenko was poisoned with an element called polonium-210. Discovered by Marie Curie in the late 19th century, polonium is a naturally occurring radioactive element found in minute concentrations in a variety of places, including inside the human body (though obviously in harmless amounts). There are many isotopes of polonium, but the isotope of particular interest in this case is polonium-210 (the 210 referring to its mass). Polonium-210 emits alpha particles which, although they are poorly penetrating, as discussed earlier, can be devastating if inhaled or ingested, as Litvinenko unfortunately discovered.

The effects of radiation poisoning, though dependent on the dose of exposure, are often predictable and brutal. In the case of ingesting an alpha-emitting radioactive material, such as in the Litvinenko case, the first signs of the trauma about to follow will typically be nausea and vomiting. As the radioactive substance passes through the gastrointestinal tract, the lining of the stomach and intestines are destroyed, breaking away. If the cells attacked by the emitted particles are not instantly killed, they may later become cancerous – though in cases such as this the victim will not survive to endure this. As the GI system is destroyed, the radioactive substance is drawn into the bloodstream and transported around the body to be further deposited in organs and soft tissues, particularly building up in the liver, kidneys, and spleen to continue the destruction of the body. The material will also reach the skin and hair follicles, causing the victim to lose most if not all of his or her hair. The bone marrow will be invaded and damaged or destroyed, causing blood cell counts to plummet (a condition known as pancytopenia). The immune system effectively begins to shut down. Cerebrovascular effects may occur, leading to confusion, convulsions and comas. Within weeks or even days the exposed victim can be dead.

geiger - wiki

A typical Geiger counter (Source: Wikimedia Commons)

Radioactive material can be highly contaminating and dangerous and, unless you happen to be equipped with appropriate radiation detection devices, you will likely be completely unaware of its presence. In the aftermath of the Litvinenko poisoning, investigators tested countless suspected areas which may have been contaminated by polonium-210. Inevitably the teapot and several areas in Millennium Hotel produced high readings for radiation. In addition to this, polonium was found in hotel rooms used by the suspects, a British Airways airplane and dozens of other locations.

Furthermore, the initial detection of radioactive material is not always straightforward. Though various devices and analytical techniques have been developed to aid in the detection of radioactive substances, not all can be successfully applied to the detection of the different types of material (ie. alpha, beta, gamma). This very problem was encountered in the investigation into Litvinenko’s poisoning. When the possibility of radiation poisoning was first raised, a Geiger counter was used to check for signs of radioactivity around his body, but readings were negative. Furthermore, bodily fluid samples were subjected to gamma spectroscopy, but again efforts were futile. The problem with these techniques was that they focussed on gamma radiation, obviously not relevant to a man who had been poisoned with an alpha-emitting substance. Eventually quick-witted scientists cracked the case and discovered the presence of polonium-210, not that the knowledge had any chance of saving the victim.

References

BBC News. Litvinenko inquiry to rule on former Russian spy’s killing. [online] Available: http://www.bbc.co.uk/news/uk-35363782

BBC News. Alexander Litvinenko: Profile of murdered Russian spy. [online] Available: http://www.bbc.co.uk/news/uk-19647226

BBC News. Litvinenko: A deadly trail of polonium. [online] Available: http://www.bbc.co.uk/news/magazine-33678717

BBC News. Russia’s poisoning ‘without a poison’. [online] Available: http://news.bbc.co.uk/1/hi/programmes/file_on_4/6324241.stm

McFee, R. B. Leikin, J. B. Death by Polonium-210: Lessons learned from the murder of former Soviet spy Alexander Litvinenko. [online] Available: https://www.clintox.org/documents/WMDSIG/AACT-WMD-Death_Polonium.pdf

Russell, J. A. Wirtz, J. J. 2008. Globalization and WMD Proliferation. New York: Routledge.

Cover Source: Wikimedia Commons

 

 

 

Forensic Failures: Eyewitness Testimony & The Ronald Cotton Trial

Forensic Failures: Eyewitness Testimony & The Ronald Cotton Trial

Eyewitness testimony is far from being a form of scientific evidence and is in fact based on perhaps one of the most flawed tools available: human memory. Despite this, the testimony of eyewitnesses can still have an enormous bearing on the outcome of a criminal investigation but unfortunately, as we will see, this evidence can range from being mildly misleading to catastrophically incorrect. And when it is the matter of someone’s life and freedom on the line, the criminal justice system cannot afford to get it wrong.

So let’s delve into a case that shows some of the great flaws of eyewitness accounts and how they can lead to devastating consequences if not treated with care.

The Case

One night in North Carolina in 1984, 22-year-old student Jennifer Thompson lay unsuspectingly in her bed when an assailant broke in, held a knife to her throat and raped her. During the ordeal, Thompson decided that she would try to remember as much about her attacker as she could, hoping to run straight to the police and get this man identified. So she took in everything she could about his face, skin colour, hair, height, weight and voice. She was convinced that she had etched this person’s image onto her brain.

Later at the police station, an investigating officer sat down with Thompson and the two of them produced a composite sketch of the rapist. This was enough for police to round up potential suspects. Thompson was later presented with a police line-up of six men (first by photograph and later a physical line-up), from which she picked out with “100 percent certainty” her attacker – a man named Ronald Cotton.

“Looking at a series of police photos, I identified my attacker. I knew this was the man. I was completely confident. I was sure”.

The suspect fit her description perfectly and he was already known to the police following a few other legal incidents, including attempted rape when he was 16. Cotton was tried, a trial at which Thompson looked him dead in the eye and declared that this was in fact the man who had raped her. Based on the victim’s testimony, and other pieces of circumstantial evidence, he was found guilty and sentenced to life imprisonment.

Meanwhile in the prison where Cotton was being held, another inmate eventually joined the ranks, a man named Bobby Poole. Poole had been convicted of a series of violent rapes and was serving consecutive life sentences. Incidentally this man bore a striking resemblance to Cotton, so much so that prison staff were constantly getting them confused. Any alarm bells ringing? Cotton subsequently confirmed his suspicions and discovered that Poole was in fact the actual rapist of Thompson. This was enough to win Cotton a retrial, but when presented with the two men, Thompson once again stated that Cotton was the attacker and she had never before seen Poole, her actual attacker. Fortunately Cotton’s break came in 1995, when he heard about a new technique known as DNA analysis. Using a semen sample collected from Thompson at the time of the attack, DNA evidence was able to prove that Cotton was innocent and Poole was the actual rapist. Case closed.

The Problems with Eyewitness Identification

The consequences of mistaken identification can be disastrous, and the people affected by this error is larger than one might initially think. In this case, an innocent man of course spent over a decade of his life behind bars for a crime he did not commit, the implications of which do not even need to be stated. The victim must then live with the knowledge that, firstly, she is in a way responsible for the incarceration of this innocent man and, secondly, her actual attacker has been on the loose! Not to mention the effects on the family of both the victim and the wrongly accused. The range of those affected can then extend to anyone who has since been the victim of the actual criminal. In this case Poole went on to rape a series of women, crimes which perhaps may not have occurred had Cotton not been wrongfully charged, forcing police to continue their investigation.

So just how can a case of mistaken identity occur?

In this instance, the assailant was mere inches away from the victim’s face for a considerable length of time (a length of time that no doubt felt like a lifetime), and yet she still made an incorrect identification. How could this happen? There are a number of factors which are known to reduce the accuracy of eyewitness identifications, many of which can into play in Thompson’s case. Extreme stress when viewing the perpetrator and the presence of weapons at the scene can affect a person’s ability to remember and recall, as can racial differences between the perpetrator and the witness. A suspect’s lack of distinctive characteristics will render them more difficult to remember, and of course the person may be wearing some kind of disguise to hide their features. The viewing conditions can drastically affect eyewitness identification too, such as the distance between the witness and the suspect, the lighting in the environment, and the length of time the witness sees the suspect (Ellis et al, 1977). In the United Kingdom following a case in 1977 (R v Turnbull), a set of guidelines relating to cases involving eyewitness testimony were introduced. These guidelines were intended to assist members of the jury in treating eyewitness evidence with the care and attention required, taking into account the circumstances surrounding the identification by the witness.

Then there are the biases that can occur as a result of the management of the investigation. The police line-up itself can introduce prejudice from the start. Had it been somehow suggested to Thompson that the perpetrator was definitely somewhere in the line-up, she may have been far more likely to choose someone even if, as in this case, he was not actually there. The process of merely being asked to choose from a selection of faces can force people to choose incorrectly. Admittedly, Cotton and Poole did look very similar at first glance, just as many people in the world share looks to a certain extent. So in Cotton’s retrial, why would Thompson still point the finger at Cotton when her real attacker was stood right there? Because reinforcement can alter memory. After years of her positive identification of Cotton being reinforced, her memory had replaced her real rapist’s face with Cotton’s. Human memory is a funny old thing, and certainly can’t necessarily be trusted.

The eyewitness statement of a witness or victim is certainly not evidence based on science, and yet this evidence can often carry such weight that the pointing finger of a witness may as well be an airtight scientific report. The Ronald Cotton case was not a one-off incident in which eyewitness testimony failed. The list of cases of people being wrongfully convicted based on eyewitness testimony, only to be later exonerated, is far longer than it should be (in fact the Innocence Project states that eyewitness misidentification has played a role in over 70% of convictions which were later overturned by DNA evidence). Looking at all the flaws of eyewitness testimony and all the cases of wrongful conviction based on it, it makes you wonder whether eyewitness testimony has any place in the courtroom at all.

References

Eliis, H. D. et al. Experimental studies of face identification. Journal of Criminal Defense. 1977(3) pp. 219-234.

Hansen, M. Scoping out eyewitness ids. Am Bar Assoc J. 2001(87).

New York Times. ‘I was certain, but I was wrong’. [online] Available: http://www.nytimes.com/2000/06/18/opinion/i-was-certain-but-i-was-wrong.html

Scientific American. Why science tells us not to rely on eyewitness accounts. [online] Available: http://www.scientificamerican.com/article/do-the-eyes-have-it

Colin Pitchfork & The Début of DNA Fingerprinting

Colin Pitchfork & The Début of DNA Fingerprinting

DNA fingerprinting, the process of producing a unique ‘fingerprint’ from a DNA sample, is something of a staple in forensic science. The ability to link a suspect to a crime scene or identify a set of remains has revolutionised legal investigations, being utilised in countless legal cases across the world since its discovery in 1984.

But once upon a time this renowned technique was just emerging, with its creator, geneticist Sir Alec Jeffreys of the University of Leicester, still unaware of just how beneficial his new technique would be to the criminal justice system. But how did this somewhat stumbled upon discovery end up becoming one of the most reliable forensic techniques available?

The story begins in late November 1983. 15-year-old Lynda Mann set off from her home in a small Leicestershire village to visit a friend, but unusually did not return. The following morning her raped and strangled body was found on a quiet footpath. Little evidence could be found other than a semen sample retrieved from her remains, though even this proved to be ineffective in leading investigators in the right direction.

But this would not be the last the world would hear of Lynda Mann. Just a few years after Lynda’s murder, another young girl went missing in July 1986. 15-year-old Dawn Ashworth had been walking home when she disappeared, her family’s worst fears soon confirmed when her brutally raped and strangled body was found two days later in the woods. Once again, a semen sample was found on the victim. The similarities between the two murders were not overlooked and, with a fresh influx of interest and evidence, the investigation could progress, with police believing the same man could be responsible for both crimes. Suspicion soon fell on Richard Burkland, a 17-year-old local who appeared to have suspicious knowledge of the latest incident. Under questioning he admitted to murdering one of the victims. Job done, the police might have thought.

Meanwhile at the University of Leicester Sir Alec Jeffreys and his team were working on a novel DNA fingerprinting technique. The technique had already been utilised in an immigration case involving a boy from Ghana, successfully proving that he was in fact the son of a family living in the UK. Recognising the potential power of this procedure and keen to apply it to a criminal case, investigators pulled Jeffreys’ and his new technique into the case.

Contrary to the belief of police, DNA profiling actually proved that Richard Burkland’s DNA did not match the semen found at the two crime scenes, pushing the investigation back to square one. Although this in itself was a ground-breaking scenario, the first ever exoneration of an innocent man using DNA fingerprinting, the murderer was still at large and the police had no more leads to follow.

With no other options, on 1st January 1987 Leicestershire Constabulary announced that they would be joining forces with the Forensic Science Service to conduct a huge DNA profiling project, collecting DNA samples from over 4000 local men in order to rule them out as suspects. However six months down the line a match had not been found. Were their efforts all for nothing?

Fortunately, a lucky break came from a particularly interesting conversation overheard in a local pub. Ian Kelly, an employee at a nearby bakery, was caught bragging about being paid £200 to submit a DNA sample on behalf of a work colleague. Living too far away from the area to have been required to give a sample himself, Kelly had apparently agreed to this request without many questions. Unsettled by the conversation, another employee soon raised the alarm, and Kelly was detained and questioned.

Kelly was covering for Colin Pitchfork, a local baker. Pitchfork had convinced Kelly that he would be framed for murder if his own blood sample was submitted, a story which was evidently enough to persuade Kelly to oblige.

On 19th September 1987, Pitchfork was arrested. After the new DNA profiling technique matched his DNA fingerprint to the crime scene samples, he admitted to raping and killing the two girls. Experts calculated the probability of this match occurring by chance to be 5.8 x 10-8. Pitchfork was sentenced to life imprisonment on 23rd January 1988.

Moral of this story – if you think you’ve gotten away with murder, you had better hope your mates don’t chat about it at the pub.

References

Bodmer, W. F. et al. 1994. The Book of Man: The Human Genome and Our Quest to Discover our Genetic Heritage. Oxford: Oxford University Press.

R v Pitchfork 2009

Featured Image: DNA Testing. [online] Available: http://upoa.biz/dna-testing

Forensic Failures: The Shirley McKie Fingerprint Scandal

Forensic Failures: The Shirley McKie Fingerprint Scandal

In light of the recent FBI hair analysis outrage, it seemed appropriate to revisit an old classic in the history of failing forensic science. The Shirley McKie fingerprint scandal. Back in the 1990s, Shirley McKie was a police constable whose life, along with an important murder investigation, was essentially ruined due to mistakes made by forensic experts.

At the beginning of 1997, 51-year-old Marion Ross of Kilmarnock, Scotland was found murdered in her home, with suspicion quickly falling on David Asbury, a handyman who had previously carried out some work on the house. A number of fingerprints were recovered throughout the investigation, including one belonging to Asbury on a gift tag in the victim’s home. Further incriminating Asbury was a tin containing nearly £2,000 found in his house, which incidentally had the victim’s fingerprints on.

But by far the most controversial piece of evidence in this case was another fingerprint recovered from the crime scene which did not belong to neither the victim nor the suspect. A thumbprint was recovered from a doorframe at the murder scene and, according to the experts of the Scottish Criminal Record Office (SCRO), that thumbprint belonged to police constable Shirley McKie.

One might think the fingerprint of a police officer at a crime scene is nothing of great note, though perhaps some slightly sloppy police work, however that was not the case. Because in this instance, Shirley McKie adamantly denied that she had ever set foot in the victim’s house. So how did her fingerprint materialise at this crime scene? Well, it didn’t. McKie was telling the truth.

Unfortunately for McKie, her claims fell on deaf ears and she was subsequently suspended, fired and then arrested by Strathclyde Police in 1998 and charged with perjury (lying under oath), even though not one of the dozens of police staff involved could recall seeing her at the crime scene. A gruelling trial ensued, dragging both McKie’s reputation and life through the mud, along with the reliability of fingerprint evidence. Four fingerprint experts from SCRO concurred that the fingerprint belonged to McKie, the same experts who had identified the fingerprint found in Asbury’s home as belonging to the victim.

The fingerprint evidence in this case became something of a double-edged sword. If the latent print comparison conducted by the SCRO was accurate, Asbury could be reasonably named as the perpetrator but Shirley McKie would surely be lying about visiting the crime scene. Conversely, if McKie was truthful in her statement, then the fingerprint evidence was flawed and the evidence against the suspect useless. With the fingerprint identification being the only significant evidence incriminating Asbury, it naturally became a vital aspect of the case. At this point in time fingerprint evidence was perhaps viewed as an infallible gold standard in forensic science, and the jury agreed that the latent print evidence presented by the SCRO was accurate, thus Asbury was convicted and McKie assumed just as guilty.

Fingerprint comparison can be a subjective technique (www.clpex.com)

Fingerprint comparison can be a subjective technique (www.clpex.com)

Thankfully the investigation did not end there. Two fingerprint experts from the U.S. were called upon to offer their expertise, and both declared that the mysterious fingerprint found in the victim’s home did not belong to McKie. The SCRO experts had misidentified the fingerprints, although they stubbornly refused to admit to this. Furthermore, a member of the Scottish Parliament somewhat unusually invited fingerprint experts from around the world to examine the prints. 171 experts from numerous countries all reached the same conclusion – that the two latent prints did not match.

The fingerprint evidence was ultimately rejected and McKie was unanimously cleared of all charges. Perhaps too little too late for a woman who had lost her reputation and career. With the fingerprint evidence rejected and McKie’s name cleared, Asbury’s conviction was also overturned, with there being nothing more than mere circumstantial evidence linking him to the crime. So through this misinterpretation of fingerprint evidence, not only was Shirley McKie’s career ruined and the freedom of a potentially innocent man put on the line, but a murder investigation was left unsolved with little likelihood of ever finding the real killer of Marion Ross.

Over the years following this trial, a number of inquiries were conducted examining why this incident was allowed to occur in the first place. Through the public inquiry it was ultimately concluded that McKie had simply been the victim of human error and nothing more, though many argued at the time that there had been something of a conspiracy and cover-up. The inquiry called for competency training of analysts and for independent reviews to be carried out of any fingerprint evidence that is disputed, along with a prompt change in the way in which fingerprint comparisons were made in the first place.

Most importantly, it was recommended that fingerprint evidence should be viewed as opinion evidence only as oppose to the product of a scientific technique that can produce absolute answers, and that experts should not make claims with 100% certainty. This problem has been once again highlighted in the recent FBI scandal, in which hair analysis experts overstated the evidence, implying the analysis was far more reliable than it actually was. Members of the jury are unlikely to have any significant knowledge of forensic techniques utilised by experts, thus are hardly in a position to determine the reliability of the methods used. It is up to the expert to highlight just how dependable the evidence really is.

Although the Shirley McKie case offered a slight silver lining in highlighting the fallibility of forensic evidence, this is evidently a lesson that is yet to be taken onboard.

References

The Guardian. Fingerprint evidence ‘based on opinion rather than fact’. [online] Available: http://www.theguardian.com/uk/2011/dec/14/fingerprint-evidence-opinion-fact

McKie, I. A. J. ‘There’s name ever fear’d that the truth should be heard but they whom the truth would indite’ (Presentation given by Iain McKie to the Forensic Science Conference 2003. Sci Justice. 43 (2003), pp. 161-165.

University of Dundee. ‘Road map for reform’ of fingerprint practices to be developed at the Scottish Universities Insight Institute. [online] Available: http://app.dundee.ac.uk/pressreleases/2011/december11/fingerprint.htm

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