Ricardo G. Federico In The News
Police hunting serial rapist don’t know who to charge after DNA leads
to arrest of identical twins
Police hunting a serial rapist in the French city of Marseille have used DNA evidence to arrest two men, but are unable to say which is the culprit because the pair are genetically identical.
After tracking down a suspect with help from video surveillance and a victim’s traceable cellphone, investigators discovered he lived with his identical twin brother, and now face the prospect of lengthy and expensive scientific testing to distinguish between their genetic codes, if that is even possible.
Identified only as Yohan and Elwin, 24-year-old brothers of mixed ethnicity, the suspects deny assaulting six women, aged 22 to 76, between September and January. The victims identified their attacker from photographs, but could not tell the brothers apart.
“It’s a rather rare case for the alleged perpetrators to be identical twins,” said Emmanuel Kiehl, the chief investigator in the case. “We must determine the exact role of each one.” He said current techniques for identifying the differences between DNA of identical twins were onerous, costly and rarely conducted in French laboratories.
It’s a rather rare case for the alleged perpetrators to be identical twins
In 2011, Canadian researchers looking into the genetic basis of schizophrenia discovered that identical twins are not exactly identical. The finding, which contradicted a long-standing assumption of applied genetics, was of particular relevance to police, who are often stumped by identical twin suspects.
Legal records in the case of Karl Strongman, for example, an Alberta man convicted of manslaughter in 2007, indicate that “he and his twin brother [Kyle] have shared court appearances and charges in the past and they have both entered pleas to charges belonging to each other.” Likewise, in 2009, identical German twin brothers managed to dodge charges over a jewellery heist at a luxury department store when investigators could not determine which of them left his DNA behind in a latex glove.
Ricardo Federico, a criminal lawyer in Ontario and adjunct professor of forensic evidence at Osgoode Hall Law School, said the Marseille case illustrates how police can work their entire careers under the impression that DNA evidence is the untouchable gold standard of forensic evidence, which convicts the guilty and frees the innocent, without ever realizing the limits of its power. As the lawyer’s joke goes, it stands for “Do Not Acquit.”
“There is a dark side to DNA. Blunders have happened,” he said. “This is not a guessing game. You can’t take two twins who share the same DNA and tell the jury or the judge, ‘Take your pick.’”
He cited an American study of cases in which DNA evidence led to clear exoneration, which found that invalid DNA evidence actually played a role in a small but significant number of the original trials.
“There are too many miscarriages of justice when it comes to science, and now you know in advance, prior to trial, that you do not have the most certain test,” he said. “This is not a tea party, this is a serious prosecution, and it’s a big price to pay as your brother’s keeper.”
If he were defending one of the twins in Canada, Mr. Federico said he would demand a judge order the most sophisticated test available, no matter the cost, or else stay the proceedings. He also said that contextual bias can add a fuzzy layer of doubt to even the most air-tight scientific test.
The scientific community should have no part in the contextual side of things
“The scientific community should have no part in the contextual side of things,” Mr. Federico said. “I don’t know how certain or uncertain these [DNA tests] are, but it seems to me that is something I would look at too.”
In the Marseille attacks, the 76-year-old woman was the first victim. After being injured by her attacker, she was forced to perform a sex act. Each rape took place at night, with the attacker striking in the entrance hall or stairwell of a building. The assailant also took the victims’ mobile phones.
“The seriousness of the crimes necessitates that an expert genetic examination is now launched and financed,” a source working on the case told the French newspaper Le Parisien.
Investigators are going through with plans to complete the “enormous” job of decoding the DNA of the suspects, then comparing it to DNA found at some of the crime scenes, which reportedly matches the twins’ “common DNA.”
La Provence, a local newspaper, reported that police were told it could cost up to one million euros for the necessary tests. It quoted a DNA expert saying that only the smallest of differences existed in the DNAs of identical twins. “For a normal analysis we compare 400 base pairs,” the expert said, adding that with twins: “We would be looking at billions.”
Scientists have demonstrated that differences in the DNA of identical twins exist. However, the process of decoding those differences is “expensive and not fully developed and remains confined to research laboratories,” said Catherine Bourgain, a specialist on the issue at the French National Institute of Health and Medical Research (Inserm).
Such complex science brings further opportunities for error in real life justice. For example Peter Hamkin, a British man who had given police a DNA sample after a drunk driving arrest, was later charged with a murder in Italy based on a false positive DNA match in a national database, even though he could prove he had never been there. He has since been cleared. And a Canadian man, Gregory Turner, faced an almost certain life sentence based on the discovery of a murdered woman’s DNA on his ring, until his lawyer discovered that the same technician who cleaned the woman’s finger nails also worked on the ring, just a few inches away, and cross-contaminated the evidence.
The Marseille twins, who are being held in custody, are said to “repeatedly use and lean on the fact that they are twins,” according to another source on the case.
National Post, with files from the Daily Telegraph