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The Atlantic has a lengthy, but informative, article on the problems with DNA testing, often seen as infallible by juries:
"Ironically, you have a technology that was meant to help eliminate subjectivity in forensics," Erin Murphy, a law professor at NYU, told me recently. "But when you start to drill down deeper into the way crime laboratories operate today, you see that the subjectivity is still there: Standards vary, training levels vary, quality varies."
Last year, Murphy published a book called Inside the Cell: The Dark Side of Forensic DNA, which recounts dozens of cases of DNA typing gone terribly wrong. Some veer close to farce, such as the 15-year hunt for the Phantom of Heilbronn, whose DNA had been found at more than 40 crime scenes in Europe in the 1990s and early 2000s. The DNA in question turned out to belong not to a serial killer, but to an Austrian factory worker who made testing swabs used by police throughout the region.
The article also notes the increasing reliance on computer processing and the desire of the firms responsible to keep the details of the processing hidden, highlighting the example of DNA-testing firm Cybergenetics and their TrueAllele software:
William Thompson [attorney and a criminology professor at the University of California at Irvine] points out that Perlin [Cybergenetics CEO] has declined to make public the algorithm that drives the program. "You do have a black-box situation happening here," Thompson told me. "The data go in, and out comes the solution, and we're not fully informed of what happened in between."
Last year, at a murder trial in Pennsylvania where TrueAllele evidence had been introduced, defense attorneys demanded that Perlin turn over the source code for his software, noting that "without it, [the defendant] will be unable to determine if TrueAllele does what Dr. Perlin claims it does." The judge denied the request.
...
When I interviewed Perlin at Cybergenetics headquarters, I raised the matter of transparency. He was visibly annoyed. He noted that he'd published detailed papers on the theory behind TrueAllele, and filed patent applications, too: "We have disclosed not the trade secrets of the source code or the engineering details, but the basic math."
Originally seen at Bruce Schneier's Blog.
(Score: 4, Informative) by Anonymous Coward on Thursday June 02 2016, @06:22PM
In 2009 some scientists figured out a way to fake DNA 'evidence' [nytimes.com] if the target's DNA profile was already in a database.
And then there was the doctor who faked out two DNA tests [wikipedia.org] by putting an ampule of someone else's blood under his skin and convincing the plebotimist to draw from it instead of his actual vein.
And last, but not least, DNA suffers from the "birthday paradox" where if you take an unknown sample of DNA and try to match it against a database, the larger the database the more likely you are to get false positives. The classic example being a white guy who's DNA matched a black guy's DNA. [latimes.com]
(Score: 2) by JNCF on Thursday June 02 2016, @07:35PM
In 2009 some scientists figured out a way to fake DNA 'evidence' if the target's DNA profile was already in a database.
Oh shit, this is horrifying. This is one of those technologies I figured the CIA probably had already. Now I know they have it, and even though we collectively know they have it DNA evidence will still be used in court against politically unacceptable individuals. Fuck. People trust their governments way too much.
(Score: 2) by frojack on Thursday June 02 2016, @09:06PM
we collectively know they have it DNA evidence will still be used in court against politically unacceptable individuals.
Well if by politically unacceptable individuals you mean murderers and rapists, yeah.
No, you are mistaken. I've always had this sig.
(Score: 2) by JNCF on Thursday June 02 2016, @09:43PM
I mean that any time a notable political dissident is accused of a crime they deny partaking in based on DNA evidence, the judge/jury should be extremely skeptical. If Cody Wilson denies being the shooter, and his DNA is on the gun, I'll give him the benefit of the doubt.
(Score: 2) by JNCF on Thursday June 02 2016, @10:25PM
Also, he did get away with it for years. After two unsuccessful DNA tests, I would probably be as skeptical of the victim's testimony as the court was. Good thing she got a detective to break into the guy's car and get another DNA sample, but too bad he still had to be caught raping again (this time a 15 year old) before they found him guilty of anything. I guess he got out with parole in four years.
(Score: 2) by JNCF on Thursday June 02 2016, @10:28PM
Bah, meant to attach this comment to a different reply to frojack [soylentnews.org], not grandparent
(Score: 0) by Anonymous Coward on Friday June 03 2016, @02:52PM
Murderers and rapists are hardly the only ones who have their DNA collected. Some states collect DNA over very minor things. Furthermore, even murderers and rapists deserve a fair trial.
(Score: 0) by Anonymous Coward on Friday June 03 2016, @02:59PM
Go lick some more boots.
(Score: 0) by Anonymous Coward on Thursday June 02 2016, @07:59PM
We should probably explain why the last link is like the birthday paradox.
In that search there was no attempt to match profile A to any given profile in the database (which would be complexity order of n), but rather an attempt to match any profile in the database to any other profile ((n * n -1) / 2 and thus order of n^2). So the even the most unlikely scenario, becomes n times more likely. If n is rather large, it becomes almost a given. But in the event of comparing a given sample to a database, the likelihood is still the same, which is very unlikely (depending on actual odds).
(Score: 4, Informative) by wonkey_monkey on Thursday June 02 2016, @08:13PM
And then there was the doctor who faked out two DNA tests by putting an ampule of someone else's blood under his skin and convincing the plebotimist to draw from it instead of his actual vein.
And not, as one may assume from reading the above, as an experiment to test DNA testing. He was a rapist trying to avoid suspicion.
systemd is Roko's Basilisk
(Score: 2) by frojack on Thursday June 02 2016, @09:02PM
Yeah, I saw that episode of Forensic Files too.
But he didn't get away with it, and its not a ruse available to the common rapist, and blood draw techniques used today prevent such a gambit.
This is way cops take you to the hospital to draw blood these days. Its so the police never get to hold your sample of pure blood.
No, you are mistaken. I've always had this sig.
(Score: 2) by JNCF on Thursday June 02 2016, @10:00PM
Having missed that episode of Forensic Files, I made the incorrect assumption wonkey_monkey was warning against. How do modern techniques prevent such a gambit? Multiple draw points?
(Score: 2) by frojack on Friday June 03 2016, @07:14PM
Once a gambit is known, its easily checked for. The case is famous enough to have made it into training manuals everywhere.
Both by the technician drawing blood, and the lab testing for preservatives pre-existing in the sample drawn.
Pushing up the guys sleeve half an inch would have revealed the surgical insertion point.
No, you are mistaken. I've always had this sig.
(Score: 2) by dry on Friday June 03 2016, @06:26AM
You mean at one time police would take your blood? That's pretty fucked. Next you'll be telling me that they don't remove two samples and make one available to the defence. Considering that taking blood is the one of the most invasive searches possible, I'd hope your courts would throw out any evidence collected that way. Or perhaps they do a strict reading of the 4th, which doesn't actually mention body fluids.
(Score: 0) by Anonymous Coward on Friday June 03 2016, @02:54PM
The fourth mentions searches of your person.
(Score: 2) by frojack on Thursday June 02 2016, @09:14PM
In 2009 some scientists figured out a way to fake DNA 'evidence' [nytimes.com] if the target's DNA profile was already in a database.
You need to follow up on that story before citing it.
Because alleles are simple encoded into numbers, knowing someone's numbers allows you to mix together blood from several sources that encodes to the same set of numbers.
That might be enough to get the computer to spit out a name.
But it IS NOT sufficient as a DNA proof, and its not sufficient for an arrest. The spit out person's blood would have to match many more alleles, with no non-matching numbers in order for the DNA evidence to be acceptable. One or two wrong sets of alleles in the sample from mixed blood would trigger alarms. Indexing in the computer is not evidence. Not for DNA, and not for Fingerprints. After you get your list of possibles, further testing needs to be done. Which is why the defense also has their own DNA and Finger Print experts.
No, you are mistaken. I've always had this sig.