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Bone Marrow Transplant Can Cause Wrongful Conviction

By Jeralyn, Section Innocence Cases
Posted on Sun Nov 06, 2005 at 11:28:45 PM EST
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When is your DNA not your DNA? When you've had a bone marrow transplant.

IT SOUNDS like an open-and-shut case: a clear DNA match is made between semen from a serious sexual assault and a blood sample from a known criminal. Yet in a recent case from Alaska, the criminal in question was in jail when the assault took place. And forensic scientists had already matched the crime sample to the DNA profile of another person who was their prime suspect. It was only after careful detective work that the mystery was solved: the jailed man had received bone marrow from the suspect many years earlier.

as forensic DNA databases expand, and more people undergo marrow transplants, the risk of a miscarriage of justice will increase. "It makes sense for investigators to be savvy to this," says David Lazer of Harvard University, who studies the policy issues surrounding forensic DNA testing.

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    Bone Marrow Transplant Can Cause Wrongful Conviction | 13 comments (13 topical)
    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#1)
    by Talkleft Visitor on Sat Dec 17, 2005 at 01:05:46 PM EST
    There's also chimerism, where different parts of the same person have different DNA. There was a documentary on one of the basic cable channels about this recently. Two women had DNA that was inconsistent with the DNA of their children. One of the women was in danger of having her children taken away and being charged with welfare fraud. Fortunately a good judge, good prosecutor and science managed to come together at the same time to prevent that miscarriage of justice.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#2)
    by nolo on Sat Dec 17, 2005 at 01:05:46 PM EST
    Sounds like we've got the plot for the next ep of CSI.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#3)
    by cpinva on Sat Dec 17, 2005 at 01:05:46 PM EST
    once again proving that fiction is nowhere near as strange as truth.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#4)
    by Talkleft Visitor on Sat Dec 17, 2005 at 01:05:48 PM EST
    Actually, the original CSI had an episode featuring chimeric DNA last season. And Law & Order SVU had one that dealt with the bone marrow donation situation. Of course, in the end, the good guys figured it all out.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#5)
    by desertswine on Sat Dec 17, 2005 at 01:05:48 PM EST
    There's also chimerism, where different parts of the same person have different DNA.
    I think I saw this in "The Man With the Sreaming Brain" with Bruce Campbell.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#6)
    by Lww on Sat Dec 17, 2005 at 01:05:48 PM EST
    The chances of this happening again are one in (DNA speak) 623,quadrillion,trillion.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#7)
    by Sailor on Sat Dec 17, 2005 at 01:05:48 PM EST
    The chances of this happening again are one in (DNA speak) 623,quadrillion,trillion.
    LWW, as we say in my field, next time show work. Generally, a given allele (the band you see on the DNA strip) might be found in 25% of the people tested. If you test any 2 people for a match you get 1 in 16. The probability that 6 alleles match is (0.25)6 or 1 in 4096. The more alleles you test the higher the odds. All of these calcs are assuming a random distribution of DNA, which doesn't exist. Families and gentypes tend to live near each other. This is yet another example of why DNA can be used to EXCLUDE a subject, but not to include one. If it doesn't match, that person/group is excluded; if it does match, at best, with the latest RFLP analysis using 13 STRs scattered over several chromosomes the odds of you matching another person are one in a trillion. This is not the same as ANY TWO people matching, that number is much lower. But none of this addresses what happens when you inject one person's DNA into another, which was what happened in this case. Makes you wonder how many folks who didn't have the $$ to fight this are incarcerated.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#8)
    by Lww on Sat Dec 17, 2005 at 01:05:48 PM EST
    I was ready to thank you for the crash course in chromosones when I spotted a discrepancy. Sailor writes, "the odds of you matching another person is one in a trillion. This is not the same as ANY TWO people matching,that number is much lower." I'm lost....

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#9)
    by Sailor on Sat Dec 17, 2005 at 01:05:48 PM EST
    LWW, think of it as the birthday game.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#10)
    by Lww on Sat Dec 17, 2005 at 01:05:48 PM EST
    Cute but no cigar. We're not talking about birthdays but birthday suita...skin and bones.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#11)
    by Sailor on Sat Dec 17, 2005 at 01:05:49 PM EST
    LWW, assuming you are serious: Prob(match) = p Prob (2 matches)= p+p-p*p

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#12)
    by Lww on Sat Dec 17, 2005 at 01:05:49 PM EST
    You're tryin to goof on me? Sailor, assuming you are serious: I guess i could ask you some firefighting questions but you wouldn't know. In Plain English(dumb people)explain the theory.

    Re: Bone Marrow Transplant Can Cause Wrongful Conv (none / 0) (#13)
    by Sailor on Sat Dec 17, 2005 at 01:05:49 PM EST
    LWW, no goof. Simplest case: 1) 3 of us stand around and flip coins to see who matches mine. I get heads. You have a 50/50 chance of matching me. He has a 50/50 chance of matching me. Together you have a 75% chance. [(.5 + .5) - (.5 * .5) = 1 - .25 = 75] 2) 3 of us stand around and flip coins to see if ANY of us match. I get heads. You each have a 50/50 chance of matching me, but if neither of you do that means you match each other. IOW, a 100% chance of a match. [.5 + .5 + .5) - (.5 * .5 * .5) = (1.5 - .125) = 1.375] Prob(match) = p Prob (2 matches) = pp, assuming independence. Prob (at least one of 2 match)= p+p-pp, assuming independence.

    Bone Marrow Transplant Can Cause Wrongful Conviction | 13 comments (13 topical)