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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."
What we're seeing here is a crack in the government's facade of fake-goodness. The ideas we're fed are that justice is blind, which means (we're taught), ultimately fair; that prosecutors and judges and the legal system in general have our best interests at heart, and so on, platitude after platitude...
But the truth peers 'round the corner here. They're not interested in accuracy, else they'd be all for determining how well this works, or not. The process and the results would both be open. What they're interested in are convictions, because that's how they keep score. That's how the public is keeping score.
This is unfair and irresponsible on two fronts. First, if you get the wrong person for any reason (including using DNA evidence that is supposed to be basically infallible, but is, in fact, fallible); then you've done a wrong to that person, of course. But secondly, for every false conviction the prosecutor and their accomplices notch into their pistols, the real criminal is now completely free -- the case is closed. They're not even looking.
As a society, we need to stop trying to raise up any part of the system based upon count of arrests, convictions, tickets, etc. The temptation to go for easy answers is too high; obviously, if the FBI itself is victim to this, an organization that prides itself on its organizational integrity, groups that have less tradition of trying to do right -- like the local cops who broke down your neighbors door last week -- are going to fall even more prey to such pressures.
As we see that the FBI tries to prevent the truth from coming out about a tool that is less effective than they claim, as they try to prevent exonerating information from reaching the defense, we see true colors.
These people are not our defenders; they claim to be, but they have their own agenda, and it is not about fairness. They're simply counting scalps.
I've fallen off your lawn, and I can't get up.
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.
Please support radical transparency and open source the government.
If everything is out in the open, there can be no hiding.
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.
if that's true why bother suppressing it and just let the do the comparisons. It'd be easy enough to bury them in regular scientific testing since the database would show that the hypothesis of these researchers is blatantly wrong and the only time being wasted is their time and not the FBI's.
Why would they (law enforcement) not want there to be some doubt to DNA results? They're also being used to overturn old convictions. In the case of current investigations, there is also other information (fingerprints, etc.) to help match a suspect to a crime...
www.joking.net
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?
As an American once arrested by the SS/FBI for computer related crime a while ago, DNA testing always worried me. I can understand it for violent offenders (which is how it was started and then carried over to all felons).
I can also tell you, if you refuse to submit to testing, they give you what they call "diesel therapy," taking you away from the cushy club fed camp you were in and busing you around the system until you relent. If you were given a half way house sentence or probation, they can revoke either for not submitting a sample.
Dispite turning my life around, finishing my degree and now working as a developer for a medium-size firm, I worry at times that one night I'll be hauled away because some flunky at the FBI mixed up DNA samples or didn't compare them correctly. I can imagine this being a horror scenario for anyone who's never broken the law, but can anyone imagine there being even a slight chance a bunch of narrow minded, non-technical cops are going to believe me, even if the crime is something totally unrelated to my history?
What we're seeing is a consequence of basic math.
1/113 billion chance a particular person has the same DNA profile as me. 6 million records. So I have a 6 million / 113 billion chance of matching someone else in the database. Drop some zeros and thats 6/113,000. Of course, each of the 6 million people in the database has a the same chance of matching someone - so that's 6/113,000*6,000,000 - which means there should be 318 people who match someone else in CODIS, or 159 'matches'.
# of people matching = size of group * size of group * chance of match
Anytime you have something that has a small chance of matching, but a fairly large sampling group, your chances of matching are high, because your chances of a match existing within the group is the SQUARE of the group size.
So it would be surprising if there were NOT people who matched in CODIS. The question is, are there more or less that 318 of them, and how much more or less?
paintball
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 FBI says that the chance of any given person matching another unrelated person is 1 in 113 billion. They claim that the reason the Arizona lab tech found as many matches as she did ("dozens") is because she was checking the whole database (6 million entries) against itself. This is a straightforward birthday paradox issue, then. According to the Wikipedia birthday problem page, the number of collisions expected given d= 113 billion different "birthdays" and n = 6 million "people in the room" is n - d + d((d-1/d)^n). This is about 160 matches! So in fact the FBI may be right. Note that the chance of a given person matching _anyone_ in the database is about 0.0053%, which is much greater than 1 in 113 billion.
If I'm not mistaken, what you've described is the Birthday Paradox:
http://en.wikipedia.org/wiki/Birthday_paradox/
I think the really cool thing about this whole story is what it says about "race". For hundreds, if not thousands of years, and even now, people have using "race" and skin colour as reasons for subjugation. But here we have the first cast of extremely close matching DNA, 1 in 113 billion, and they are from different "races". Wow.
This, if anything, should dispel any stupid theories about the difference of "race" within the human species.
I match 12 out of 12 Y-DNA markers with 9 other people who have had their DNA tested. Based on our last names, none of us are related.
I don't think you should be able to use blind searches of a DNA database as evidence, because it's too easy to get false positives. It's only useful evidence against someone you've already found by other means, or as a way to generate leads.
Any sufficiently unpopular but cohesive argument is indistinguishable from trolling.
"We have to refocus everyone on the Rights of the Innocent"
No, we need to focus on rights and fairness, period. Cops aren't always truthful. Drug dealers sometimes don't lie.
Renaming basic human rights and due process, i.e. Rights of the Innocent, to some special "needs" category plays into special interest. Much like how "victim rights" laws throw to the wind fair court cases; the defense has their name thrown in multitude of papers and intense scrutiny, while the victim hides in anonymity. This has resulted in inequities in handling of cases--this become hugely apparant in both the Duke rape case and the Kobe Bryant rape case; consider these were big name cases where the flaws were apparant and utilized by the prosecution. (If you're wondering what should happen--if the victim's name is protectd in a case, the defense's name should also be protected in the case.)
Furthermore, such new terminology often is at some point redefined and abused--most of the citizens of the United States still don't realize that "violent" offenses constitute mere drug use or sex (so called statutory rape) under the 1984 Bail Reform Act (this is why California's 3 strikes laws ends up taking in so many repeat offenders). I can easily see "rights of the innocent" laws being ineffective and creating a special class as one-time DUI offenders now accused of murder get denied a "special class" of rights.
The facts are rather simple--for the past 60 years, laws have gone overly pro-prosecution. Part of this is government keepign score, as someone else put it. Part of this is also on the general public for being stupid, scared, and greedy--why people will look less horrified at a murderer than a pet killer, or if they see someone shackled they presume guilt, or see some sick social advantage in another person being locked up (prison doors open as the economy tanks means more jobs for the "innocent" sort of thinking).
Not to troll, but law enforcement agencies are really more interested in convictions than the truth. For instance, Virginia has a law that places a 21-day time limit on new evidence that can be used to exonerate someone wrongly convicted. I'm sure the FBI doesn't want it's coveted CODIS database subject to any doubt.
It must have been something you assimilated. . . .
. That is to say, the chance of having marker A might be 1% and the chance of having marker B might be 5%, but the chance of having BOTH might very well be higher (or lower) than .05%.
IANAFG (I am not a forensic geneticist) but the co-segregation of genetic markers is such a fundamental and well understood process that 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.
Of course the statistics they calculate are probably based on estimates of pairwise segregation. Some higher-order effects may be at work that change the statistics relative to a basic model like independent pairwise segregation.
For example, allele A of gene 1 and allele B of gene 2 may not segregate according to a previously measured pairwise stastistic in the presence of allele C of gene 3. Such higher-order effects may have a significant impact on the statistics but would require a *lot* of data to reveal.
Just callin' it like I see it.
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.
Remember the "birthday problem"? "How likely do you think it is that any two people in this classroom have the same birthday?" Most of the kids take a quick look around, see ~30 people in the room, know there's 365 days in a year and think--not very likely. But there's usually a match. In a classroom full of kids, the probability that any two children have the same birthday is (we'll ignore leap year for simplicity) 1/365. We need to know the probability that none of the kids have the same birthday. The probability of there being no collisions between two kids is still 1/365--this is just a more useful wording of the criterion. So, first 2 kids, probability of a collision: 1/365 Third kid--if his b-day lands on either of the first two kids' you get a hit: 2/365 Fourth--3/365 chance of a collision. ...
And, of course, if you had 366 kids in the room, the last one's a sure thing.
You multiply the probabilities a series of independant events to get the probability of the whole series.
If we have 30 kids and 365 days, we want to know the chances of 30 misses (no collisions) in a row.
If P is the probability of something happening, then probability of NOT (something happening) is 1-P
So, probability of 30 misses in a row will be 1-(1/365) * 1-(2/365) * 1-(3/365) * ... * 1-(30/365).
Which is ~.2703.
So, 1-.2703 tells you that if you've got 30 kids in the room you've got nearly a 3/4 shot at two of them having the same birthday.
Quickly iterating through the same process in oo.o calc for an FBI database with... ...ability to recognize 113E+09 unique DNA profiles ...DNA from a million folks (no idea how many of us they really have)
gives you .988 probability of collision.
BTW, the general formula for the "birthday problem" is written as follows:
P=d!/[(d-n)!(d^n)]
Where
P=probability of no collisions
d=number of days in the year
n=number of students in the sample
"Reality is that which, when you stop believing in it, it doesn't go away." - Philip K. Dick
And this is relevant how? You've already told us they were distinct people, this doesn't make them more distinct.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
As I've said time and time again. Forensic science is a scam. Second rate statisticians and second rate politicians team up with second rate scientists and second rate TV shows to convince the public that forensic superheroes can detect evidence of any evil crime you commit. It's just a way to keep the people under control.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Unchecked state power is a danger to everyone. The FBI's court filings to prevent DNA statistical studies are transparently self serving. Imagine if they got their wish and had everyone in their database. Million of innocent people would be subjected to unreasonable suspicions. Such plans should be abandoned and all efforts made to release people who were wrongly convicted, something that DNA testing seems to be good for. Great injustice has been done because the state granted itself the power to punish based on what it considered reasonable extrapolation instead of truth backed up by real data. It reminds me of witch trials.
Prison violence proves that surrendering your rights to the state does not make you safe. All kinds of state wards have suffered all kinds of abuse in direct proportion to the control and trust guardians are given. It is nearly impossible to administer justice in a place where no one is trusted but abuse must always be checked for and discouraged. This is one of the reasons state supported torture is so horrible. A cruel state that is more interested in punishment and revenge than it is in justice and protection will abuse guilty and innocent people alike. The ultimate abuse, however, remains the loss of life.
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?
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.