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FBI Fights Testing For False DNA Matches
Statesman writes "The Los Angeles Times reports that an Arizona crime lab technician found two felons with remarkably similar genetic profiles, so similar that they would ordinarily be accepted in court as a match, but one felon was black and the other white. The FBI estimated the odds of unrelated people sharing those genetic markers to be as remote as 1 in 113 billion. Dozens of similar matches have been found, and these findings raise questions about the accuracy of the FBI's DNA statistics. Scientists and legal experts want to test the accuracy of official statistics using the nearly 6 million profiles in CODIS, the national system that includes most state and local databases. The FBI has tried to block distribution of the Arizona results and is blocking people from performing similar searches using CODIS. A legal fight is brewing over whether the nation's genetic databases ought to be opened to wider scrutiny. At stake is the credibility of the odds often cited in DNA cases, which can suggest an all but certain link between a suspect and a crime scene."
Unless the crime labs start encoding the full DNA sequence, even then identical twins will duplicate, the best DNA, for that matter finger prints, can do is prove it is *NOT* that person.
It is hard to believe the FBI won't do the study to get real numbers, but we've been here before. These are the same people who presented bullet lead evidence with equal certainty. The science is impressive but it means nothing when your original premise is wrong. In the bullet lead case, it turns out that matches were common and single boxes often had differences. The coincidence between two people is good reason to review the data and make sure DNA statistics are correct. Until that is done, the odds of DNA matches should be looked on with great skepticism.
It's screw ups like this that make the death penalty a bad idea. While life in prison is a terrible punishment, perhaps more cruel than death, it gives the state a chance to fix its mistakes.
DMCA, Hollings, Palladium. What might have sounded like paranoia is now common sense.
Questions:
1) How wrong is it?
2) Why is it wrong?
3) Who is responsible for this blunder?
Quite possibley this can kill DNA evidence. Somebody was more interested in convictions than the truth here. Despicable.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
There has never yet been a 13-locus match seen between unrelated people in the national database- despite the 5 million or so profiles currently in it. I'm sure the average Slashdot reader can manage to work out how many pairwise comparisons that is. (Hint- it's a pretty fucking big number.)
Well it seems that your statement of 'never' is simply because that comparison has not been run, since the FBI is doing everything possible to prevent testing of that theory. If its so unimaginably rare, it would seem that the FBI would be all for doing these searches to bolster the value of their evidence. However the results in MD would seem to challenge that dogma.
A 9-locus match between unrelated people is not surprising. That's why we don't sue only 9 loci, idiots!
Well it seems that California prosecutors are idiots and were using a 9 locus match to prosecute a man for a 2 decade old murder. From TFA: "Its implications became clear as she prepared to defend a client accused of a 20-year-old rape and murder. A database search had found a nine-locus match between his DNA profile and semen found in the victim's body. Based on FBI estimates, the prosecutor said the odds of a coincidental match were as remote as 1 in 108 trillion." So just to explain why we 'idiots' would use a 9 locus match: DNA collected at a crime scene is not a complete genome. Often it is only fragments. You may not have a full 13 loci to check because the fragment you have would not cover all 13 loci. There is, however a statistical nicety here that you've completely side-stepped in your haste to call us morons (which TFA mentions). The likelihood of finding matches of 9 of the 9 you have in your genome fragment is far less than the likelihood of finding any two people in a database with 9 of any 9 of 13 loci that match.
From the description, this seems like an example of the birthday problem. Briefly, in a group of 23 people the odds are 50-50 that two of them will have the same birthday, while in a group of 57 the odds are better than 99%. However, the odds that someone in the first group will share *your* birthday are far less, roughly 6.1%. Quoting the Wikipedia article, "For a greater than 50% chance that one person in a roomful of n people has the same birthday as you, n would need to be at least 253. Note that this number is significantly higher than 365/2 = 182.5: the reason is that it is likely that there are some birthday matches among the other people in the room."
Likewise, the odds of there being two people with matching DNA in a database are far higher than the odds of someone else matching *your* DNA. So it seems possible that the FBI could be quoting accurate odds, while at the same time there being lots of matches within the database.
Nothing for 6-digit uids?
That's about a 1/500 chance of a random match, good evidence but not the 1/1E12 claimed. The FBI needs to get off it's extrapolation and study the data.
What's really threatened is Big Brother's DNA database. If the evidence is not conclusive, there's little reason to spend billions collecting it from school children. A lot of equipment makers will cry about that.
The LA Times says dozens of similar matches have been found. I have learned not to trust the media when they use questionable terms like "similar." By similar did they mean that in all of those other cases, 9 (or more) of the 13 genetic markers used were matched like they were in this one case? Or is the paper trying to make it seem more severe by saying dozens of similar instances exist, but these cases only match a couple of the marker--not nine markers. While this one example throws some questions into things, I want some more numbers before I start wasting a lot of money redoing every DNA test. Things such as scandal and fear sell papers. Using words such as similar allow writers to make things sound much worse than they might be. This sells papers.
The other question is: since the database was started, our ability to study DNA, examine genetic markers and recognize which areas are better for identifying individuals has drastically improved. Has the database improved to match this knowledge, or are we relying on outmoded methods? If the former, then it's as good as it is going to get - for now. If the latter, the probability of a false positive could be massively slashed. That would surely be desirable for a crime-fighting system... wouldn't it?
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
So what you are saying is that a new sample has a 1 in 19,000 chance (6e6/1.13e11) of finding a match in CODIS at random, even though this is a new sample not present in the database. With thousands of police departments nationwide running samples against CODIS every week, false matches like this may occur frequently. If the consequence is that an innocent person is charged or even convicted of rape or murder, this is frightening.
There is a big difference between telling a lay jury "this match had a one in a 113 billion chance of occurring at random" versus "this is an event that occurs randomly on a routine basis." Non-statisticians have a hard time getting their head around the concept of correction for multiple hypothesis testing.
The real problem is that the FBI match criteria were developed years ago when the CODIS database was small compared to its current size, and these criteria have not been updated in light of growth in the database and new technology. Using state-of-the-art genotyping technology, it should be possible to design a test with a small chance of a false positive match even if the database contained the entire US population.
Statesman
Just wait until they start outsourcing prisons to China. Won't that be all kinds of fun?
God, I wish I were joking.
God invented whiskey so the Irish would not rule the world.
Mod my parent as a dupe. I should read further before posting. People below me have posted this already. And while you are at it, mod them up. :P
Who's being targeted, or who's committing more crimes?
Occam's razor comes into play here.
committing a crime doesn't necessarily make you a prison statistic.
Being sentenced to prison does. It's cool you saw "Contact", though.
This would be true, but not everyone who matches is going to be able to have committed the crime. For example, a lot of the people who are in the Database are in prison. That is a pretty good alibi. Many of the people are going to be so far away geographically from the crime committed that they will be dismissed as suspects after cursory investigation. The odds of a false positive get MUCH smaller require that the false positive sample in CODIS must come from someone who is close enough to the crime scene and lacks a credible alibi.
There's a difference. A prosecutor in the situation you give is placing his own career interests above the interests of justice and the law.
A defense lawyer getting someone off "on a technicality" is at the very least demonstrating an allegiance to the letter of the law and a commitment to see that all people are treated under the law equally... and often may be the last line of defense against a government bent on violating civil rights.
There's really no such thing as "getting off on a technicality." Whenever you hear that phrase it's coming from a prosecutor or police officer who at the least didn't do their job properly and at worst violated the law themselves, and got caught.
When the police searched you illegally, you "got off on a technicality."
When they came into your home without a warrant, you "got off on a technicality."
When they didn't properly document and control the chain of possession of evidence used to convict you, thus throwing into doubt whether it's even legitimate evidence, you "got off on a technicality."
When they interrogated you improperly or otherwise throw into question the accuracy of what they claim is your testimony to police, you "got off on a technicality."
When they selectively show your photo to or otherwise lead the victim into presupposing you are the guy who did it, you "got off on a technicality."
When the prosecutor has withheld information that might have exonerated you or changed a jury's verdict, you "got off on a technicality."
"Got off on a technicality" = not guilty.
This space available.
I've noticed something: government conspiracies always get modded up here and are usually based on "Think about it. You know it's true, man."
The reason overly pessimistic posts about the government get modded up and not overly optimistic ones seems to be that your average slashdotter is insecure and doesn't want to get lauged at for being naive.
Well call me naive, but I don't think things like this are driven by greed so much as incompetence, hubris, and an "us vs them" mindset.
Only if you assume that "race" is an entirely genetic category, and not a product of culture and surrounds.
Also, these tests only check (I believe) up to 13 specific sequences. These sequences are the ones most likely to be different between individuals - they're not going to use the sequences for stuff like skin colour, because those would have large number of individuals with the same sequence.
If you match someone else on these tests, it means that you have a certain number of highly-variable sequences in common with them. It doesn't necessarily mean that if you compared the full DNA strand they'd be remotely similar (once you've factored out the large proportion of DNA that all humans have in common).
Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
I recommend you read a book like Sense and Nonsense About Crime and Drugs. Our justice system is biased from the top down. For an example, the percentage of black and white drug users is exactly the same; last I read around 13%. However, a minority is more likely to be searched during routine police encounters by the police, more likely to be arrested, more likely to be tried, more likely to be convicted, and more likely to be sentenced to jail time. So, we go from equivalent percentages of black and white drug users to a wildly overrepresented percentage of black inmates on drug offenses; last I read 58%. Also consider that law enforcement often takes a "containment" approach to drug enforcement. To paraphrase a Chris Rock joke, if a 14 year old can score weed you think the cops don't know where the drug dealers are, too?
I swear to God...I swear to God! That is NOT how you treat your human!
"If they truly cared about justice they'd say "hey we need to take another look at this". I don't know how they can live with that on their conscience anymore than I understand how defense lawyers can live with setting rapists and killers free on technicalities."
There's a difference. A prosecutor in the situation you give is placing his own career interests above the interests of justice and the law.
No, no, no. Three words explain why the prosecutor doesn't want to re-try the case and why this is the right thing to do in the circumstances: adversarial justice system.
It may not be the best system, but it's what we have; it is the duty of the prosecution to assume that they are right, just as it is the duty of the defence to assume that the prosecution is wrong. To allow the prosecutor to pick and choose the circumstances in which to present a strong case vs the circumstances in which to side with the defence introduces more bias into the system. Each side must present their case as if it was absolutely the way that they say it is, and then the jury must weigh the circumstances and decide.
Race IS genetic, and only a product of culture and surroundings in that they may have influence over mating.
Nevertheless, pure races (with distinctive racial phenotypes) become harder to be found. Us humans have made "pure breed" dogs, horses or fightbulls in centuries or less; pure races that would disappear if left in the wild. We tell dog races apart from the size, the color and length of their hair, the face bones, the tail, etc. We tell men races apart grossly from the amount of melanin alone. Still the mainland chinese and the japanese are very different, as are the norse and ukranians (both blue-eyed blondes).
In the human species, races sprung up from a group of humans becoming geographically (or culturally) isolated and resorting to inbreeding. Nowadays we overcome geographical isolation easily, but still races endure because of cultural isolation.
Westeners tend to look at themselves as the root of all evil race issues, but I can resort to HUGE human groups in Africa, the middle east or the far east that won't mate someone from the tribe next door even though we'd be unable to tell them apart from average africans, arabs or chinese.
In this case, loci were chosen that vary a lot among individuals, regardless of race. There may even be matches with monkeys or other mammals! This does not take race differences apart, nor does prove it as a social construct; otherwise albino black or chinese people wouldn't "look" black or chinese.
With such optimists, what we need pessimists for?
I would have a hard time believing that they wouldn't know and correct for the rates of their chosen set when calculating the probabilities of a matched set.
And I would have a hard time believing that the prosecution gives a damn whether what they present is accurate as long as they can get the conviction. I have yet to see a prosecutor in real life who's more concerned with finding the truth than getting the conviction.
The situations I'm talking about are not those. A prosecutor that withholds evidence he knows may be exculpatory is not a prosecutor assuming he is right - that's a prosecutor being corrupt.
The examples I gave are not examples of the adversarial justice system.
They are examples of civil rights violations. They are examples of unethical behavior. They are examples of government corruption. They are examples of crimes.
A prosecutor fighting retrial over a disagreement over the validity of evidence is an example of the adversarial justice system.
A prosecutor fighting retrial over evidence they improperly and knowingly withheld is not - it's an example of a criminal trying to cover up his crime.
Prosecutors and police are not always simply motivated by doing their jobs properly. They, like other people, are also motivated by greed, personal ambition, prejudice, personality flaws.
"The Authorities" lie and break the law. Not rarely - routinely.
This space available.
I do know where you're coming from, and I'd certainly hate to be considered a conspiracy nut. I do try to liberally apply the idiom "never attribute to malice what can be adequately explained by incompetence".
All that said, however, I'm not really seeing a reason here that can be explained by simple incompetence. If they are, at heart, good people, then they would want to know how accurate DNA results are. It wouldn't even expose them to looking bad if it turned out that they'd been using bad evidence - all they'd need to save face would be a photo of an FBI agent shaking hands with someone in a lab coat and a press release explaining how grateful they are for having this weakness in the testing system found. Any other ideas on why they'd want this not to be looked into?
I think the answer is that most lawyers in general lack a conscience, you'd have to to be successful.
Disclaimer: my bar exam is a week from Tuesday.
I've had this conversation with people before, its why I want to stay out of criminal work. I guess the theory is that you throw everything on the table and hope that the opposing attorney is doing their job. That's the adversarial system. The Constitution dictates that the prosecution has to throw a lot more on the table. Ethics rules dictate that the prosecution also has to defeat their own case when they have information that will damage it. The defense attorney just has to do the best he can with the facts he is given.
Its easy to malign both sides of the system. However, neither is an easy task. The prosecution is ethically responsible for both society's interest, and to some extant, the defendant's as well. The defense attorney is responsible for the defendant's interest but, to a broader extent, society's interests as well. Defense attorneys protect even you and me in the sense that those accused of crimes, whether innocent or guilty, set the periphery of our legal protections. Guilty people have been responsible for the liberties you and I enjoy because they challenged the procedure, actions, and level of proof employed by the government. Whether or not an attorney is scum or devoid of conscience, there is an attorney on the other side taking them to task. Sure its an imperfect system, but its the best society can come up with and we muddle through.
Why have 1 person driving a backhoe when you could employ 20 with shovels?
(apart from the article not even mentioning the birthday paradox) is this:
A database that gets corrupted by searching in it? Jesus.
Ok, continuing with your unprovable premise, perhaps the blacks are just not as smart and tend to get caught more?
Anyone that sees the 'lopsided' amount of black people in prison compared to white really needs their head examined. There is no sinister conspiracy involved here, its just how the chips are falling, for whatever reason.
---- Booth was a patriot ----
There are several "layers" of causality that you have to get through from "population of random 100k people of certain race" to "locked in jail".
Asserting that the only causality is some sort of discrimination without also examining the other layers is just plain old intellectual dishonesty.
Being targeted or not, if you don't do the crime it's pretty hard to end up in jail. Overall society's expectations are pretty clear, even in the depths of whatever crap-ghetto culture you came from. Everybody knows if you do certain stuff you get busted despite peer pressure of "whitey keepin the black man down" every 4 year old knows "gun in pocket = jail". If they choose not to care, how the fuck is that society's fault?
Well call me naive, but I don't think things like this are driven by greed
Call me cynical, but I think you're very naive.
You can't take the sky from me...
Your statement flies in the face of the call for equal protection under the law. It is not wise to try to justify the outrageous situation we are under. To deny the inherent racism and classism is much worse than intellectual dishonesty. I hope that's not what you are doing.
What?
Any other ideas on why they'd want this not to be looked into?
It's human nature not to want to admit mistakes, even to yourself. These people have spent years convicting people on DNA, and in the mind of the public it's rock solid -- if they have you on DNA, case closed.
The upheaval in the court system will be huge. All cases where DNA evidence was used will have to be retried. Throw in the mentality of "we know he's guilty anyways" based on other evidence, and it's not surprising that the FBI would rather sweep this under the carpet.
The idea that the FBI is part of some conspiracy to get slave labor is absurd.
Oh ye of little experience. You actually believe the cops are so squeaky clean, do you? Corruption permeates much more deeply than you apparently believe. And you don't seem to understand the resources needed to prove one's innocence, instead of pleading it down. That there will make you a statistic. For shame!
What?
Why should it have to be fair? if one segment of the population just happens to commit and get caught more often, thats just how it is. There isn't some hidden agenda or magic happening.
If they want fair, they can stop committing crimes..
Now, i fully agree there might be individual officers that improperly profile ( and don't forget some profiling is more then proper ), but the overall system does not.
---- Booth was a patriot ----
If you think it says i'm bigoted, you didn't understand my signature in the slightest..
---- Booth was a patriot ----
True, but willingness to have people rot in jail rather than admit to a mistake (even a colossal screw up like this) *IS* malice.
Mere incompetence went out the window when the FBI started their efforts to sweep this under the rug (along with the likely falsely convicted).
That doesn't make a slave labor conspiracy, but, I'd say malice on the part of law enforcement is quite bad enough.
It's a nice idea, but if you do that then you risk people erring too far on the side of caution. If I was on a jury and there was a risk of me being punished for finding the defendant guilty then it is likely that I would vote not guilty (even if I strongly believed based on the evidence presented that he/she was guilty). Ideally you want your judges/juries to be impartial, but if they have something to gain/lose then they no longer have that impartiality. Sure, some of them will make bad decisions every now and then, but at least they will make bad decisions for the right reasons.
I like my coffee the way I like my women - roasted and ground up into little tiny pieces.
corollary to "honest men have nothing to fear from the law" should be "honest government has nothing to fear from facts"
FreeBSD for the impatient.