mick silver
15th March 2016, 09:50 AM
People Are Going To Prison Thanks To DNA Software — But How It Works Is SecretSource: BuzzFeed (http://www.buzzfeed.com/stephaniemlee/dna-software-code)Two days after Christmas 1977, police found Shelley H. dead in her apartment in Long Beach, California. The 17-year-old had been sexually assaulted and strangled (https://www.documentcloud.org/documents/2755132-LBPD-Press-Release.html): She waslying (http://www.courts.ca.gov/opinions/nonpub/B258569.PDF) on the end of her bed, her feet touching the ground, with an electrical wire tied around her neck. Vaginal swabs were taken during her autopsy, but at the time, there was no DNA testing. So the samples went into storage, and the case went cold for the next three decades.
Then in 2011, a private DNA lab matched the samples to a man who had lived in Long Beach at the time, Martell Chubbs. The DNA, according to his attorney, is the only evidence linking him to the victim.
And these DNA samples were particularly tough to read, tangled with the genetic traces of one or two people in addition to Shelley. What were the chances that the match was correct? Dr. Mark Perlin, the CEO of a Pittsburgh company calledCybergenetics (http://www.cybgen.com/), said his computer program could figure it out.
In pop culture, DNA is often portrayed as a magical piece of evidence that links perpetrators to crimes and exonerates the innocent. But deciphering it is usually much messier in real life, especially in cases like Shelley’s that involve samples of more than one person’s DNA. Over the last decade or so, forensic scientists have come to realize that traditional methods for interpreting these “mixed samples” are often less reliable than previously thought.
Now, Cybergenetics and a handful of other companies are selling a solution: software that claims to interpret mixed DNA with a high degree of accuracy. These companies point toseveral (http://onlinelibrary.wiley.com/doi/10.1111/j.1556-4029.2011.01859.x/full) peer-reviewed (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092837) studies (http://www.ncbi.nlm.nih.gov/pubmed/23948322) that (http://www.sciencedirect.com/science/article/pii/S1872497315000265) describe the underlying mathematical concepts of their programs, as well as results of mock testing in which they correctly interpreted known samples.
But here’s the problem, according to some attorneys and geneticists: These companies claim that the details of how the computer programs carry out their calculations, spelled out in their source codes, are trade secrets. So there’s no way to independently verify that the programs are pinning the real criminal, critics say.
“It’s a black box,” said Angelyn Gates, an attorney based in Pasadena who’s defending Chubbs, now 56, from a murder charge for the 1977 crime. That trial is expected to happen this year in Los Angeles County, and she’s trying to prevent the prosecution from introducing Cybergenetics’ software, called TrueAllele, into court.
“You have a defendant’s right to cross-examine and determine, ‘How are you saying this is the result in my case?’” Gates said. In her view, “Perlin says, ‘Who cares about your constitutional rights? I want my money.’”
Since 2009, TrueAllele has been used in more than 500 cases and helped convict robbers, child molesters, murderers, and rapists across the U.S. and the U.K. Another program,STRmix (http://www.esr.cri.nz/), has been used in thousands of cases in Australia and New Zealand since 2012. Just last month, in two double homicide cases near Pittsburgh, judges rejected (http://www.post-gazette.com/local/city/2016/02/11/Defense-lawyers-in-Wolfe-sisters-case-seek-source-code-from-DNA-expert/stories/201602110067) both defense attorneys’ requests to examine TrueAllele’s source code. In December, a Michigan (http://www.mlive.com/news/muskegon/index.ssf/2015/12/michigan_judges_landmark_dna_r.html)judge allowed STRmix to be used in a case, marking one of the first times it has been admitted into a U.S. court.
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Then in 2011, a private DNA lab matched the samples to a man who had lived in Long Beach at the time, Martell Chubbs. The DNA, according to his attorney, is the only evidence linking him to the victim.
And these DNA samples were particularly tough to read, tangled with the genetic traces of one or two people in addition to Shelley. What were the chances that the match was correct? Dr. Mark Perlin, the CEO of a Pittsburgh company calledCybergenetics (http://www.cybgen.com/), said his computer program could figure it out.
In pop culture, DNA is often portrayed as a magical piece of evidence that links perpetrators to crimes and exonerates the innocent. But deciphering it is usually much messier in real life, especially in cases like Shelley’s that involve samples of more than one person’s DNA. Over the last decade or so, forensic scientists have come to realize that traditional methods for interpreting these “mixed samples” are often less reliable than previously thought.
Now, Cybergenetics and a handful of other companies are selling a solution: software that claims to interpret mixed DNA with a high degree of accuracy. These companies point toseveral (http://onlinelibrary.wiley.com/doi/10.1111/j.1556-4029.2011.01859.x/full) peer-reviewed (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092837) studies (http://www.ncbi.nlm.nih.gov/pubmed/23948322) that (http://www.sciencedirect.com/science/article/pii/S1872497315000265) describe the underlying mathematical concepts of their programs, as well as results of mock testing in which they correctly interpreted known samples.
But here’s the problem, according to some attorneys and geneticists: These companies claim that the details of how the computer programs carry out their calculations, spelled out in their source codes, are trade secrets. So there’s no way to independently verify that the programs are pinning the real criminal, critics say.
“It’s a black box,” said Angelyn Gates, an attorney based in Pasadena who’s defending Chubbs, now 56, from a murder charge for the 1977 crime. That trial is expected to happen this year in Los Angeles County, and she’s trying to prevent the prosecution from introducing Cybergenetics’ software, called TrueAllele, into court.
“You have a defendant’s right to cross-examine and determine, ‘How are you saying this is the result in my case?’” Gates said. In her view, “Perlin says, ‘Who cares about your constitutional rights? I want my money.’”
Since 2009, TrueAllele has been used in more than 500 cases and helped convict robbers, child molesters, murderers, and rapists across the U.S. and the U.K. Another program,STRmix (http://www.esr.cri.nz/), has been used in thousands of cases in Australia and New Zealand since 2012. Just last month, in two double homicide cases near Pittsburgh, judges rejected (http://www.post-gazette.com/local/city/2016/02/11/Defense-lawyers-in-Wolfe-sisters-case-seek-source-code-from-DNA-expert/stories/201602110067) both defense attorneys’ requests to examine TrueAllele’s source code. In December, a Michigan (http://www.mlive.com/news/muskegon/index.ssf/2015/12/michigan_judges_landmark_dna_r.html)judge allowed STRmix to be used in a case, marking one of the first times it has been admitted into a U.S. court.
Read More... (http://www.buzzfeed.com/stephaniemlee/dna-software-code)Share This Article...