

Innocent man jailed for 8 months after DNA match - rwmj
http://www.bbc.co.uk/news/science-environment-19412819

======
droithomme
A basic understanding of statistics is sufficient to understand how this
happens. Authorities have become obsessed with the idea of assembling giant
DNA databanks of entire populations and then doing _"cold hits"_ for unsolved
crimes against the entire database.

The problem with this is that DNA testing is not 100% accurate, and when you
test an entire population you're going to start getting false positives. The
larger the population, the more false positives.

But then a jury may be told "there was a 100% DNA match" or that "There is a
less than 1 in a billion chance that he is not the killer." And the wrong guy
goes to prison.

Check out this other recent cold hit case. They took DNA samples from Occupy
Wall Street protesters and then ran them against unsolved crimes files with no
connection to the protesters just to see what they could get.

[http://www.kens5.com/news/DNA-match-in-cold-case-murder-
call...](http://www.kens5.com/news/DNA-match-in-cold-case-murder-called-
error-162369036.html)

So a protestor is arrested and charged for a 2004 murder based on this. Later
found to be an error, but getting to that point assumes you can afford a good
lawyer. There are lots of people getting charged for unsolved crimes they have
no connection to. Not all of them can afford a lawyer and expert witnesses.

New York recently passed a law requiring DNA samples from all persons
convicted of any crime, even misdemeanors such as loitering.

[http://www.npr.org/2012/03/15/148692189/n-y-passes-dna-
requi...](http://www.npr.org/2012/03/15/148692189/n-y-passes-dna-requirement-
for-convicted-criminals)

There is a nationwide push for mass DNA collections. Other jurisdictions are
pushing to take DNA of people who are merely arrested, regardless of whether
there is a later conviction.

[http://chronicle.augusta.com/news/crime-
courts/2012-09-01/so...](http://chronicle.augusta.com/news/crime-
courts/2012-09-01/south-carolina-collect-dna-after-every-felony-arrest)

> South Carolina’s law enforcement agency will soon collect DNA samples from
> people when they’re arrested for a felony – rather than post-conviction –
> four years after legislators passed a law requiring the state’s DNA database
> to expand.

This push to states even comes from the federal level:

[http://www.acluofnorthcarolina.org/?q=congress-votes-
expand-...](http://www.acluofnorthcarolina.org/?q=congress-votes-expand-
taking-dna-arrest)

<http://thomas.loc.gov/cgi-bin/query/z?c111:H.R.4614>:

> In a 357-32 vote, the House voted to offer cash incentives to states that
> start taking DNA upon arrest for certain crimes.

It even has it's own lobbying group: <http://www.dnasaves.org/>

> Every day innocent people needlessly become victims of violent crimes. Most
> of these are committed by repeat offenders. By passing state legislation
> that enables law enforcement to collect DNA from felony arrestees, at the
> same time as fingerprints, your state can catch criminals sooner

There you can see that 26 states now mandate collection on arrest. More than
half of the 50 states.

Supreme Court Chief Justice John Roberts has ruled that DNA sampling on
arrest, regardless of conviction, is permissible:

[http://www.huffingtonpost.com/2012/07/18/dna-collection-
mary...](http://www.huffingtonpost.com/2012/07/18/dna-collection-
maryland_n_1683931.html)

The US has a nationwide database now that they do cold hits on, which is a
statistically questionable process.

<http://www.bioforensics.com/news/relatives_6-05.html>

> Since the mid-1990s, the USA and the United Kingdom have maintained
> databases that use a series of such alleles to match DNA from unsolved
> crimes to known or suspected offenders. In the USA, states and the federal
> government keep DNA indexes of suspects and unsolved crimes, and share
> information through a computer system maintained by the FBI.

"Guilt by the Numbers: How fuzzy is the math that makes DNA evidence look so
compelling to jurors?" by Edward Humes was an article that covered the
problems here pretty well.

Original is gone, but here it is in cache:
[http://webcache.googleusercontent.com/search?q=cache:www.cal...](http://webcache.googleusercontent.com/search?q=cache:www.callawyer.com/clstory.cfm%3Feid%3D900572%26ref%3Dupdates)

More information about the case discussed in that article and the problems
with the cold hit methodology:
<http://articles.latimes.com/2008/may/04/local/me-dna4>

There are also various articles by DNA cold-hit advocates who claim it is
invalid and cold-hits are a good practice, for example this article:

[http://lawprofessors.typepad.com/science_law/2009/04/taking-...](http://lawprofessors.typepad.com/science_law/2009/04/taking-
liberties-with-the-numbers.html)

Doing blind searches of samples on large DNA databases in order to find cold
hits gives you a very high probability of a false match. A match that the
falsely accused defendant will be quite difficult to challenge since there is
a general belief by the public that DNA matches on a few markers are
irrefutable proof of identity.

DNA can more strongly connect a suspect who is already known through other
information. Doing blind searches isn't science and it isn't justice.

[http://www.bioforensics.com/articles/Legally%20Scientific%20...](http://www.bioforensics.com/articles/Legally%20Scientific%20\(Cold%20Hits%20vs%20Hard%20Facts\).html)

> For instance, if a DNA test capable of distinguishing between 'unrelated'
> people with one million to one confidence was used to create a database of
> two million personal profiles from a population of 20 million potential
> suspects you could be pretty certain that most crime stain profiles run
> against it would produce at least one cold hit.

> You could also be more than 90% certain that it would be the wrong cold hit.
> You could further expect that around 80% of the personal profiles on the
> database would match at least one other on record from a different person.

> Problems like these had led the 1996 National Research Council publication
> "The Evaluation of Forensic Evidence" (NRC-II) to recommend that "When the
> suspect is found by a search of a DNA database, the random match probability
> should be multiplied by N, the number of persons in the database".

On one side we have an argument that there are severe statistical problems
with this. On the other side we have those who claim that is false and that
the chance of any DNA match being wrong are so small as to be virtually
impossible. Yet every year the number of false accusations and convictions
from cold hits grows, as we see in this latest case.

~~~
brazzy
It's maddening how badly almost everyone sucks at understanding and
interpreting statistics (including many who have had significant training in
doing so), and chilling when that is combined with a forensic method that is
at heart statistical.

OJ Simpson got away with murder because the jury didn't understand statistics,
and now more and more innocent people go to jail because juries and judges
don't understand statistics.

------
tokenadult
The lede paragraph in this interesting article raises the key question:

"Scientists, lawyers and politicians have raised new concerns over the quality
of forensic evidence testing - so is the criminal justice system too reliant
on lab tests without realising their limitations?"

I'm grateful for some of the specialized publications on a skeptical
worldview, such as Skeptic magazine and Skeptical Inquirer magazine and some
of the websites and books recommended in those magazines, for teaching over
the last decade or more that even "scientific" approaches to questions that
come up in court cases have often never been validated. I was surprised to
discover that even the old technique of matching fingerprints is still the
subject of a lot of recent scholarly studies

[http://scholar.google.com/scholar?q=fingerprint+matching+val...](http://scholar.google.com/scholar?q=fingerprint+matching+validation)

[https://uchastings.edu/hlj/archive/vol59/Koehler_59-HLJ-1077...](https://uchastings.edu/hlj/archive/vol59/Koehler_59-HLJ-1077.pdf)

and that there is NOT full validation of all the techniques that have long
been used to show fingerprint matches between criminal case suspects and
fingerprint impressions found at a crime scene. The article submitted here
makes the important point even the latest gee-whiz technology, DNA typing,
which is usually the key to solving crimes on television drama shows, has
significant limitations. Sometimes DNA samples are poorly gathered, and
sometimes DNA test results are ambiguous.

It takes a combination of multiple lines of evidence that are consistent with
one another best to prove guilt beyond a reasonable doubt. Lawyers for
criminal defendants do the right thing when they argue vigorously over every
factual basis for the state's claim that an accused defendant is guilty. I was
an appellate clerk once upon a time for a state supreme court that reviewed
all first-degree murder convictions in the state. I had to read a lot of case
files with gory crime scene photographs and lots of transcripts of witness
testimony to events and expert witness testimony about the findings of
scientific tests. Sometimes a case is supported by so many lines of evidence
that no reasonable appellate judge could doubt the sufficiency of the evidence
shown at trial. Other times a conviction at trial is reversed on appeal not
because of factual innocence, but because of legal errors by the prosecution.
But every once in a while, even after a conviction at trial under the standard
of presuming innocence beyond a reasonable doubt, a very reasonable doubt that
wasn't considered fully at trial is preserved in the court record and forms
the basis of reversing the trial court judgment on appeal. No one line of
evidence is foolproof, not even DNA.

------
DanBC
> his DNA sample was on record after he had willingly given it to them as part
> of an investigation into a burglary at his mother's home some years earlier.

This is a worrying snippet. Many people in the UK think that DNA databases
should include every citizen. There are often local campaigns of "have your
DNA taken, get ruled off our suspect list" when there are murders or multiple
rapes.

The police have pushed to include as many DNA profiles as possible.

They don't realise that false positives happen.

Keeping a DNA database of just the criminals means that you don't have to
store information from 60 million people (approx current UK population), nor
process unneeded data to find matches, nor worry so much about false
positives.

The good human rights stuff drops out as a result of good data practices.

~~~
tsotha
>There are often local campaigns of "have your DNA taken, get ruled off our
suspect list" when there are murders or multiple rapes.

Really? That's just daft. Why would anyone who isn't actually a suspect be
susceptible to that line of reasoning?

~~~
anothermachine
"Are you hiding your DNA because you know it matches a crime scene, perhaps?
Let's have you down to the station for some more detailed interrogation."

That's why.

~~~
tsotha
They have a term for that kind of government - "police state".

------
Alex3917
DNA testing and forensics in general is a complete scam. Most of it has
already been proven to be pseudoscience or else is on its way to being proven
so. And of the stuff that actually is at least potentially legit, like DNA
testing, virtually all of the labs in the US are so poorly run that their
results wouldn't even be admissible as evidence, let alone considered
reliable, if more people actually knew what was going on there. If I remember
correctly the last time the US government did an audit of its accredited
forensics labs every single one failed, and the vast majority aren't even
accredited to begin with.

Relevant links:

[http://www.alternet.org/print/story/147613/has_the_most_comm...](http://www.alternet.org/print/story/147613/has_the_most_common_marijuana_test_resulted_in_tens_of_thousands_of_wrongful_convictions)

[http://www.newyorker.com/reporting/2009/09/07/090907fa_fact_...](http://www.newyorker.com/reporting/2009/09/07/090907fa_fact_grann?currentPage=all)

[http://www.nytimes.com/2011/11/27/magazine/dna-evidence-
lake...](http://www.nytimes.com/2011/11/27/magazine/dna-evidence-lake-
county.html?_r=2&ref=magazine&adxnnlx=1322497624-TcXf3srEhTm8YyMhyeuvpQ&pagewanted=all)

[http://reason.com/archives/2011/02/21/the-mind-of-a-
police-d...](http://reason.com/archives/2011/02/21/the-mind-of-a-police-
dog/singlepage)

<http://www.erowid.org/freedom/police/police_article1.shtml>

[http://www.pbs.org/wgbh/pages/frontline/criminal-
justice/rea...](http://www.pbs.org/wgbh/pages/frontline/criminal-justice/real-
csi/can-unconscious-bias-undermine-fingerprint-analysis/)

~~~
shardling
>DNA testing and forensics in general is a complete scam

 _What?_ Every single one of those links either supports DNA testing or
doesn't mention it.

It's certainly true that a lot of forensics turns out to be borderline
pseudoscience or superstition (everyone should read the newyorker link when
they have time) but don't just lump everything together.

(Also don't lead with a link to alternet unless you want bias readers against
you!)

~~~
Alex3917
"Every single one of those links either supports DNA testing or doesn't
mention it."

Did you read the NYT article?

Also, the issue isn't whether DNA testing could work in theory if it were done
by academics under ideal conditions. The issue is whether or not the DNA
testing that's actually done by forensics labs is A) accurate (not
contaminated, read properly, etc.) B) used correctly by the courts. It also
assumes that the police aren't planting evidence against suspects, either
purposely or accidentally, that the chain of custody is maintained, etc. There
is very little reason to think that these things are always the case.

~~~
shardling
>Did you read the NYT article?

Yes. Could you point to the specific part you feel is relevant?

~~~
Alex3917
The whole premise of the article is that if the DNA matches, the prosecutors
argue that you're guilty, and if the DNA doesn't match, the prosecutors argue
that you're guilty anyway. If the results of a forensic 'test' show that
you're guilty no matter what the outcome, that's pretty much the very
definition of a sham. They might as well be using a truth-telling chicken.

~~~
shardling
That is not the picture the article actually paints.

~~~
Alex3917
"The unnamed-lover theory has been floated so often that defense lawyers have
a derisive term for it: 'the unindicted co-­ejaculator.'"

~~~
shardling
It was also _unsuccessful_ in a great many of those cases.

Prosecutors don't determine whether you're guilty or not -- the issue isn't
what they say, but whether juries believe them.

The article was about how prosecutors are very unwilling to accept DNA
evidence, not about systematic problems with its interpretation.

------
computator
> _His DNA sample was on record after he had willingly given it to them as
> part of an investigation into a burglary at his mother's home some years
> earlier._

Lesson to everybody: Don't ever voluntarily give your fingerprints or DNA.
Once they get into the government databases, you can (a) never retract them
(and nor can you change your fingerprints or DNA), and (b) you can fall victim
to false matches.

Here's a similar case of a false match -- in this case for fingerprints:

Portland-area lawyer Brandon Mayfield was arrested in May 2004 because his
fingerprint matched one found on a bag of detonators near the train station in
Madrid in the March 11 2004 bombing, which killed 191 people. But Spanish
authorities said the fingerprints belonged to another man, an Algerian. A US
federal court later threw out the case against Mayfield, and the FBI expressed
regret for the "fingerprint-identification error". As a former Army officer,
Mayfield's fingerprints would be on file with the government. A law
enforcement official said the fingerprints were not on file because of any
crime or as part of the government's terrorism databases.

------
carbocation
Forensics is not my field, but genetics is. Restriction enzyme digestion and
gel electrophoresis seems to be the technique that is still being used for
forensic DNA matching.

To my mind, it would make a lot more sense to simply genotype a few hundred
well-chosen (highly variable) SNPs on a standardized array. Since there are
premade arrays that give you tens to hundreds of thousands of SNPs for a few
hundred dollars, you should easily be able to unambiguously identify a single
individual even if (non-monozygotic twin) family members are in the haystack.

Obviously this says nothing about guilt, but from the DNA matching perspective
we can and should do better.

~~~
datr
I imagine it depends on the lab. A friend worked as an assistant at a place
that did forensic dna matching five years ago and she definitely used your
suggested method.

------
pfedor
It is of course very unfortunate that this man had to spend 8 months in jail.
There was no lab error in this case (the man was a cab driver with a rare skin
flaking condition and his skin flakes stuck to the nail polish of a passenger
who was later the victim of murder). But of course errors do happen, someone
in this thread quotes a 1% to 2% error rate for DNA testing.

Buit to put it in context, according to the Innocence Project, in 25% of the
cases when DNA testing is used by the FBI during the investigation, it results
in the suspect being exonerated. That 25% is a large number of innocent people
who would be charged and tried and a lot of them would be convicted if not for
the existence of DNA testing.

Read this interview if you have a moment:
[http://www.slate.com/blogs/thewrongstuff/2010/08/17/reasonab...](http://www.slate.com/blogs/thewrongstuff/2010/08/17/reasonable_doubt_innocence_project_co_founder_peter_neufeld_on_being_wrong.html)
and then tell me whether you still think DNA testing is not a force for good.

------
rayiner
Forensics is a total sham. <http://lst.law.asu.edu/FS09/pdfs/Koehler4_3.pdf>

The error rate of fingerprints is at least in the single digit %, but
everything else is double-digits. Moreover, while DNA is theoretically
extremely reliable, the error rate of DNa testing is dominated by lab error
and is on the order of 1-2%. Yet, juries are generally not told this overall
error rate, but rather just the theoretical probability of a false match (1 in
trillions).

~~~
vishaldpatel
Wouldn't it be the defense attorney's responsibility to remind the jury of the
error rates time after time?

~~~
jlgreco
Attacking the reliability of DNA evidence can make you seem desperate. Of
course they still need to do exactly that, but you are not just combating what
the prosecution said (or failed to say) but what the jurors already "know".
They "know" DNA is perfect magic evidence that gets the badguy every time on
CSI.

------
SoftwareMaven
I was quite surprised when reading "The Drunkards Walk" when he talked about
DNA evidence. The rates of false matches is really quite low (like one in tens
of million chance if memory holds) as long as there are no errors in the lab.
But there are. In fact, the odds of an error on the lab are on the order of
one in 200. And juries aren't allowed to be instructed on that.

~~~
vibrunazo
> And juries aren't allowed to be instructed on that.

Why?

~~~
rprasad
Because the defense must first provide some evidence that a mistake was, or
could have been made, in order for the jury to receive such an instruction.

~~~
lutusp
> Because the defense must first provide some evidence that a mistake was, or
> could have been made ...

No, they only need to describe the statistical probability of an error -- they
don't need to uncover specific evidence that an error was made in a particular
case. And they can empanel expert witnesses to describe the kinds of errors
that are typical of the method, but again, without having to uncover evidence
unique to the present case.

~~~
mvc
> And they can empanel expert witnesses to describe the kinds of errors that
> are typical of the method

Presumably that's beyond the reach of a defendant on legal aid.

~~~
lutusp
> Presumably that's beyond the reach of a defendant on legal aid.

Yep. Some might call that a defect in our legal system (that fair
representation is out of reach of indigent defendants). Others, cynics all,
might assert that if you can't pay for the justice, don't do the crime.

------
delinquentme
sounds like someone couldn't read a gel electrophoresis ? How long did they
run the gel for ? Accuracy can be increased in a read with a longer gel ...
Were they using some 4" gel ? There are tons of variables. And as stated in
the article some of them aren't even running the right tests.

~~~
lutusp
It's worse than that. As the article points out, we shed cells everywhere, and
the possibility exists that the test was conducted fairly and accurately, but
it doesn't prove what the prosecutor claimed -- that the DNA proved guilt. All
the DNA proved was that the defendant's DNA was present where the measurement
took place, but this doesn't necessarily mean the defendant was ever there, or
was present at time time of the crime.

~~~
FuzzyDunlop
It also alludes to the separation of concerns in forensic examinations
creating a new set of problems. For example, the DNA testers had a sample to
test, and little to no knowledge of the greater context.

~~~
billswift
On the other hand without separation of concerns, you get the risk of the lab
"finding" what the investigators wanted, like the incidents in the FBI labs in
the 1990s.

