When DNA lies

Is DNA testing an infallible tool in the hands of Justice; a dangerous weapon in the hands of the police; or an invasion of innocent citizens’ privacy?
by Ellie Ismailidou

Published December 19th, 2010,  'To Vima on Sunday’ print and online edition
See online version in Greek here 
See print version in Greek here:
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It was a cold afternoon in November 1968 when the authorities discovered the body of thirteen-year-old Jane Durrua in a field behind the railroad tracks of Middletown, Connecticut USA. They announced that an unknown man had raped the student, strangled her, and dragged her body to where it was later discovered. The perpetrator was never found. Thirty-six years after the murder had taken place, in August 2004, an announcement that shocked America was issued by the New Jersey prosecutor, Mr. John Kay. "Through DNA testing, we put a face to the killer of Jane Durrua, and that face belongs to Jerry Bellamy.” The accused was a fifty-two year old man who had recently been arrested for sexual assault in Atlantic City. The sample of genetic material that underwent DNA analysis appeared to be an exact match to the sample that had been found on the underwear of the thirteen-year-old victim thirty-six years earlier. Bellamy was tried for rape and murder of the first degree. Justice triumphed! Or did it? Two years after Bellamy’s arrest Mr. Frank Rogers, Connecticut state police deputy superintendent of investigations, was forced to publicly admit that DNA…doesn’t always tell the truth. The DNA analysis of the sample on the victim’s underwear and that taken from Bellamy for the completely irrelevant case of Atlantic City had been examined in the same laboratory, by the same technician, on the same day. The chance of cross-contamination between the two samples was quite significant. Subsequent testing was unable to corroborate the match and Jerry Bellamy was released. DNA testing was officially no longer infallible.

A miniscule amount of genetic material, a spot of blood, a drop of saliva, a strand of hair accidentally left at the crime scene, are now enough for scientists to identify a perpetrator and solve mysteries that even Hollywood’s best detectives would be hard pressed to decipher. Even as we all proclaim DNA testing’s absolute accuracy, what do we really know about its reliability? Can it really always catch the bad guy? “Everything is a matter of statistics. DNA analysis records 10-16 genetic markers which are actually small sections of DNA with sequences of nucleotides that appear with a certain frequency within the population. If the first marker appears at a frequency rate of 1 in every 133, and the second at a rate of 1 in every 183, the combined frequency of these two markers is once in every 24,339. By adding one more marker with a frequency of 1 in every 123, the combination of the three markers appears once in every 2,993,697 people. In practice, that means that only one out of three million people can possess that genetic material. By combining five, six or fifteen genetic markers the statistical implications of DNA testing produce odds in the 99.9 percentile. There’s no way to discuss 100% certainty, however,” Dr. S. Alahiotis, professor of genetics at Patras University, explains to the 'To Vima on Sunday'.

The 'tangled' helix

In a laboratory where thousands of samples are processed each day things get complicated. Is there a possibility that the genetic material being tested could be contaminated with someone else’s DNA? That’s a very real possibility! In order to analyze a microscopic sample of DNA from a drop of saliva or a strand of hair, we use the method of polymerase chain reactions. What that means, is that through a biological process we are multiplying the few cells in a sample a million times until we have enough material to analyse. If, however, the sample is contaminated, even with a fleck of saliva, or a few of the researcher’s skin cells, then those too will be multiplied by a million,” Dr. Lina Florentin, molecular biologist and President of the Geneticists’ Association of Greece, informs us.

The laboratories of the Hellenic Police Force and the forensic scientists responsible for analyzing DNA samples in criminal cases take a series of measures to avoid contamination. The suspects’ genetic samples are stored separately, and analyzed in different locations, at staggered time intervals. When a positive identification is made, second and third reexaminations follow to confirm the finding,” explains Ms. Ioulia Skitsa, biochemist, and head of the Athens forensic DNA analysis laboratory. “Even in the case of contamination from a second source, the results would clearly show two separate and distinct genetic profiles, making it virtually impossible to mislead the researchers,” she adds. One of the few published comparative studies revealed that from 2003 to 2007 the Santa Clara District Attorney’s forensic lab recorded fourteen instances of DNA samples contaminated by the researcher, three instances of contamination from an unknown source, and six instances where DNA samples from separate cases were cross-contaminated. A total of 23 mistakes in four years! Maybe that’s not so bad? A founding legal principle – also known as Blackstone's formulation – states, “Better a thousand guilty persons escape, than that one innocent suffers.”

Dr. I. Anagnostopoulos, professor of Criminal Justice at the Athens University Law School, points out the importance of not deifying the results of DNA testing, but rather using it as one part of a larger body of supporting evidence, evaluated with the same scrutiny as any other diagnostic tool. Lets not forget that all a positive DNA match does is identify a person at the crime scene, it does not describe how the crime was committed! It proves that the person in question was at the crime scene, not that the identified person is the perpetrator. Part of the responsibility of casting the evidence in the appropriate light falls to the skills of the defense attorney whose job it is to make sure that neither the judge nor the jury are being duped,” he comments. At the same time geneticist Mr. G. Fitsialos emphasizes that “While Greek law states that only publicly run labs are approved to provide DNA analysis identifications, it is permissible for the defendant to test a sample of genetic material at a privately owned and operated facility and present the results to the court as a piece of physical evidence. This gives the defense the opportunity to confirm the test results”.

Genetic surveillance?

In the summer of 2009 a law was passed that allowed for the creation of the first DNA bank in Greece's history. Pursuant to article 200 of the Greek Criminal Procedure Code the bank will be under the jurisdiction of the Criminal Investigations Unit of the Hellenic Police Force and regulated by the appeals prosecutor. “We finally did something other than talking about the problem and made a real step in the right direction! We need to recognize the fact that many serious crimes are committed by serial offenders. Committing one rape is a serious offense… having committed ten is that much more serious. By using the DNA bank as a resource we will be able to eliminate repeat offenders”, Mr. F. Koutsaftis, director of the Athens Forensic Service, tells the 'To Vima'. The legislation in question has deeper implications, however. As Dr. Elisavet Symeonidou Kastanidou, professor of Penal Law at the Aristotle University of Thessaloniki’s School of Law, explains, “whereas before 2009 the analysis of genetic samples was permissible only for specific categories of violent crimes, a DNA sample deposit is now a mandatory requirement for all offenses, as well as for any misdemeanours punishable by at least a three month sentence.” The actual implementation of the law means that genetic samples are being collected for anything from a shoplifting charge to a defamation suit! The scope of the new law is causing practical problems, to say nothing of the invasion of personal privacy, which is often disproportionate to the gravity of the crime. The forensic laboratories of the Hellenic Police Department are backlogged with over 3,500 samples awaiting processing and more flowing in every day, logged and collected for every minor offense.

Dr. I. Naziris, who holds a Ph.D. in criminal justice and a position as a special guest lecturer at the Aristotle University of Thessaloniki’s School of Law, stresses the fact that the current law stipulates that in the event of a positive identification resulting from DNA testing, the genetic code is stored until the death of the individual. “Note that the law does not stipulate that DNA be stored only if the identified individual is convicted, but merely if there has been a ‘positive identification’. This means that an innocent individual may be unlucky enough to have been present at a crime scene from which a DNA sample has been collected. This individual will have a record of their 'genetic fingerprint' in the police database for the rest of their life! Examples such as these seem to be at odds with the workings of a just state,” Dr. Naziris adds.
The advantages and the dangers
+ A miniscule amount of genetic material is enough for scientists to identify a perpetrator
+ The certainty of the test reaches the 99.99 percentile
+ Thanks to the creation of a DNA bank a perpetrator can be identified, even if there is no other evidence apart from the genetic sample
+ The test can decipher cases that remained unresolved for decades and lead to the exoneration of the wrongly convicted
– The possibility of contamination might lead to the conviction of the wrong person 
– It is often ‘deified’ and as a result other substantial evidence is undermined
– Collecting genetic samples for minor offenses leads to a backlog of thousands of samples awaiting processing 
– A genetic sample could be ‘planted’ (ex. by leaving a hair strand at the crime scene) in order to fool the authorities
The Verdict is in on DNA Testing

Convicted due to DNA testing

In 1998 a young woman was raped by two men, one of whom according to the victim was Josiah Sutton from Houston, Texas. Forensic scientists testified that the DNA analysis of one of the sperm samples found at the crime scene matched Sutton’s. They claimed that the other sample belonged an unidentified second man. Sutton was convicted and received a sentence of 25 years. Four and a half years later his appeal to reexamine the DNA evidence was approved, resulting in the admission that a mistake had been made and he had been falsely convicted. The crime scene revealed the genetic material of only one man, and that man wasn’t Sutton!

In 2005 Gary Leiterman from Michigan, USA, received a life sentence for a murder that had been committed almost forty years earlier. The whole story began when his genetic profile was identified as a match to DNA samples found at the crime scene. A drop of blood found on the victim’s hand pointed to the genetic profile of another man who was only four years old at the time of the murder. Therefore, the prosecutor was convinced that he had cracked the case. Since the four-year-old couldn’t possibly have committed the murder, Leiterman must have been guilty. It was later proven, however, that both samples - Leiterman’s and the other man’s - happened to have been in the same lab at the same time due to the investigations of two totally unrelated cases. To this day, some geneticists still claim that there has been a contamination of DNA samples

Acquitted thanks to DNA

Joseph Abbitt, from North Carolina, USA, spent 14 years behind bars for two rapes he didn’t commit. He was convicted in 1995 on faulty witness testimony but a DNA analysis performed in 2009 proved that Abbitt was innocent.

Marvin Anderson, from Virginia, USA, was convicted in 1982 and sentenced to 210 years of incarceration. He was found guilty of having committed two rapes and a robbery on the basis of unreliable testimony and manufactured evidence. A DNA test performed in 2002 proved his innocence which resulted in his release

Fooled the System

In 1999 Anthony Turner from Milwaukee, Wisconsin, USA, who was serving time for a rape conviction, managed to smuggle a sperm sample to the outside world concealed in a ketchup bottle. His family bribed a woman to stage a fake rape using Turner’s sperm. Turner’s goal was to prove the unreliability of DNA evidence, which had been a major factor in his own conviction.

Dr. John Schneeberger from Saskatchewan, Canada, was subpoenaed to give a blood sample for DNA testing when on trial for the rape of one of his patients. He surgically inserted a tube of another man’s blood into his arm and managed to fool the authorities.


DNA testing... on the Silver Screen
The endless possibilities of DNA analysis haven’t left the movie business untouched. More and more films and television programs feature heroes who manage to solve cases with DNA testing; some corrupted villains even tamper with the genetic evidence in order to mislead the fictional authorities. In Beyond a Reasonable Doubt Michael Douglas plays a corrupt prosecutor who manages to win a series of convictions by planting genetic evidence at crime scenes. Millions of viewers tune into the hit television series CSI to watch investigators scan crime scenes and then manage to identify the culprit from a mere drop of sweat. In the same vein, the popular series Bones is based on a group of FBI anthropologists who succeed in solving cold murder cases by testing DNA samples taken from the victims’ bones.