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Twins' DNA Foils Police 209

Hugh Pickens writes "The Telegraph reports that James and John Parr were both arrested after watches worth £10,000 were stolen from a shopping center. Police found blood on a piece of glass at the scene of the crime and traced it back to the 25-year-old identical twins through DNA tests. But James and John both denied the theft and, because they have identical DNA, it has been impossible to prove beyond a reasonable doubt which twin is responsible. 'The police told us that they knew it was one of us, but we both denied it,' says James. 'I definitely know I didn't do anything wrong. I was watching my daughter that night.' Now the Crown Prosecution Service (CPS) has concluded that it cannot prove beyond reasonable doubt who was responsible. 'Unless further evidence becomes available, we are unable to authorize any charge at this time,' says CPS spokesman Rob Pett. 'This is certainly not something that we regularly encounter.' Identical twins have hindered police investigations a number of times since the advent of DNA testing. In Malaysia last year, a man suspected of drug-smuggling and sentenced to death was released when the court could not prove whether it was he or his twin brother who committed the crime."
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Twins' DNA Foils Police

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  • Re:Um, this is easy (Score:4, Interesting)

    by Threni ( 635302 ) on Saturday April 03, 2010 @01:51PM (#31717086)

    And which one cut himself opening catfood. You don't go to prison for cutting yourself feeding your cat, right?

  • by goodmanj ( 234846 ) on Saturday April 03, 2010 @02:11PM (#31717332)

    ... not as defendant, but as a juror.

    I served on a jury last summer for a case of armed home invasion. The victim, if you can call him that, was a multiply-convicted white crack user. The victim claimed the defendant forced his way into the defendant's house with a gun, as part of a dispute over the defendant's missing cell phone following a drug deal.

    The defense attorney's goal was to convince us that there was no way to determine beyond a reasonable doubt whether the defendant committed the crime, or his brother. The police did a horribly sloppy job of gathering evidence, the DNA was so contaminated that while it matched the victim, it also had good odds of matching the defendant's brother or about 1 in 5 random people off the street. The victim lied on the stand several times and showed no reliability as an eyewitness, and all the other evidence (phone calls, evidence collected at defendant's house) pointed to *some* member of the defendant's family, but no way to know who.

    So we found him not guilty. Kind of a shame since the defendant probably *was* a drug dealer, but no way to prove it wasn't his brother. And the kicker: if they bring the brother to trial, he can use the same defense.

  • by Kozz ( 7764 ) on Saturday April 03, 2010 @02:12PM (#31717334)

    If the twins have not been living near-identical lives (sharing cars, apartments, etc), they probably have distinct bacterial colonies, and bacterial forensics (an emerging science) could be the key. []

    This method cannot conclusively place an individual at the scene of the crime, but if combined with DNA evidence, I think you'd have a pretty air-tight case.

  • by stonewallred ( 1465497 ) on Saturday April 03, 2010 @06:12PM (#31719120)
    Eh, people were buying donated blood back in the day to leave as evidence. Guy robs stores, fakes cutting hand, leaving a nice blood sample, and if he is ever caught, the blood type doesn't match, and he goes free. And I always liked the idea of visiting several self-car washes and grabbing the bags from the trash cans and vacuums. That way you can make a nice assortment of random evidence to leave, all of it clearly pointing away from you.
  • Re:You joke but... (Score:3, Interesting)

    by JWSmythe ( 446288 ) <> on Sunday April 04, 2010 @12:36AM (#31721500) Homepage Journal

        I went reading up on it, beyond Wikipedia. :) Most of it was stating the statistical impossibility of DNA matches. They were all forensic reports used by the police, so it's in their best interest to say it. Come court time, forensic reports will outweigh Wikipedia.

        I do recall reading in the past that "identical" twins do have different DNA. Sure a sample of a few markers may show an identical result, but if they did better tests with more markers, they could easily determine who the blood "donor" was. If the 13 in 300,000 number is correct, with a population of 1 million, you'd potentially have 43 duplicates. I'm assuming that there was other police work done to even attempt to match these two guys, but that assumption is likely wrong.

        They didn't say how many markers were used in this test.

        I've actually read up a good bit on DNA testing. My mother has been tracking our family tree back for many generations. There are a few companies that have large databases of DNA, so you can match potential family members, although separated generations ago, who may have information on the tree that may be otherwise unavailable. "Family bibles" were a great resource, and were generally handed down over the generations. They'll frequently list all births, deaths, and marriages, so someone in a branch of the tree 5 generations ago may have some key information. I believe they would only link the trees, and not actually give up the information on the living members of the family though.

        In reading their information though, I found that they weren't testing enough markers, which could lead to false positives, and even fail to match distant family members. There was not enough advantage for me to include myself in it. Unless there was a good chance of success, and a valuable source of information to be had, it wasn't worth putting my DNA into some corporations database regardless of how warm and fuzzy they made their privacy policy sound. I don't trust the government, and I trust corporations even less. For all I know, I may match the twins in the article on a sample of just a few markers. I'd hate to find out that law enforcement had access to the database (although quietly), and I'd suddenly become a suspect due to flawed methodology. I'd actually be safe in this case, being on the wrong side of the pond and all. :)

        I do appreciate that DNA testing has exonerated people from crimes. A definite negative is still a negative no matter how you look at it. I'd hate to be that guy who had a positive due to insufficient testing, and rot in jail for someone elses crime.

Nondeterminism means never having to say you are wrong.