Posts Tagged ‘DNA identification’

The use of DNA identification as a forensic tool, beginning in 1989, changed the way that we think about guilt, innocence, and traditional police investigation.  It isn’t just the 311 wrongful convictions that DNA identification has confirmed; it’s the far more numerous cases in which DNA has determined guilt — sometimes in cases years or decades old.

Now DNA identification is about to change: it will become even more powerful than it is now.  A new way of processing and interpreting DNA has arrived that will make our current DNA techniques look weak by comparison.

On Friday, Nov. 8, I attended an incredibly interesting talk by Dr. Ria David.  Dr. David is one of the co-founders of Cybergenetics, a company based in Pittsburgh.  Cybergenetics has perfected computer-based techniques and technologies that will change the way that DNA is analyzed.  With Cybergenetics’ TrueAllele (R) system, the analysis relies the power of computers instead of interpretation done by humans.   The talk was sponsored by the Center for Women’s Entrepreneurship (CWE) at Chatham University.  (Disclosure: my wife runs CWE; my wife and I know Dr. David and her Cybergenetics co-founder, Dr. Mark Perlin, but neither my wife nor I have any personal or financial ties of any kind to Cybergenetics.)

Most of us know that a DNA sample allows forensic scientists to say things like “the odds that this sample came from anyone other than the defendant are fifty million to one.”  Pretty powerful stuff — until you learn that Cybergenetics’ systems will allow prosecutors to offer juries odds of not tens of millions to one, but trillions or even quadrillions to one.  In addition, Cybergenetics will allow analysts to pull apart mixtures of DNA from different people, which is common at crime scenes, and which current DNA technology often can’t handle.  Readers of my book Failed Evidence: Why Law Enforcement Resists Science can get a little more information in Chapter 7, pp. 186-190; you can get the book here.

Cybergenetics’ DNA system has found ready acceptance in the United Kingdom, but the process has been slower in the U.S. There has been considerable resistance — something readers of Failed Evidence are quite familiar with — particularly at the FBI, which governs current DNA protocols and use.

There is much more to how the Cybergenetics’ TrueAllele system works, and what it can do; I’d urge readers to take a good look at Cybergenetics web site, which gives details on what they do, and the many criminal cases and mass disaster identification cases (including the identification of remains at the World Trade Center site).  Once law enforcement sees what this new method of using DNA can do, and once resistance to change is overcome, DNA will be able to identify many more guilty criminals, as well as exonerate many more of the wrongfully convicted, and it will do so with more certainty that we ever thought possible.


In today’s world, we think of DNA matching as the gold standard of identification: a scientifically precise method of matching human tissue or fluids left at a crime scene to a particular individual.  But in an op-ed article last week, High-Tech, High-Risk Forensics, published in the New York Times, Cal Hastings professor of law Osagie Obasogie reminds us that even DNA identification isn’t foolproof.  It’s an excellent point and one worth remembering.  But then he stumbles over the details of DNA identification, labeling it high risk, because many people might have the same DNA profiles.  Risk is always present, but is the risk of getting DNA identifications high because many people might have the same DNA profile?  No.

Professor Obasogie tells us the story of a man arrested for a murder near San Jose, California, when his DNA was found on the victim’s body.  Only after the man was arrested and jailed did his alibi surface: at the time of the murder, he was a patient at a hospital, suffering from severe intoxication, and there were voluminous records to prove it.  He was freed after five months, and prosecutors now think the most likely explanation is that paramedics who transported the man to the hospital were the same ones called to the crime scene later that night.  The DNA was likely transferred to the victim from the paramedics’ clothing or equipment.  Professor Obasogie decries “the certainty with which prosecutors charged Mr. Anderson with murder,” because it  “highlights the very real injustices that can occur when we place too much faith in DNA forensic technologies.” This is hard to argue with; for those who can remember this far back, it recalls lawyer Barry Scheck cross-examining Dennis Fung in the O.J. Simpson murder trial over the sloppy collection of DNA and other evidence.  Scheck and other lawyers argued that the DNA that seemed to implicate Simpson just couldn’t be trusted; “garbage in, garbage out.” Professor Obasogie is not saying that the paramedics did anything wrong or were sloppy in any conventional sense; rather he’s arguing (correctly) that contamination can happen even when we’re not aware of the possibility.  Thus caution is always advisable, even with DNA.

But then Professor Obasogie begins to argue that there are deeper problems with DNA identification than just contamination.

Consider the frequent claim that it is highly unlikely, if not impossible, for two DNA profiles to match by coincidence. A 2005 audit of Arizona’s DNA database showed that, out of some 65,000 profiles, nearly 150 pairs matched at a level typically considered high enough to identify and prosecute suspects. Yet these profiles were clearly from different people.

Professor David H. Kaye of Penn State Dickinson School of Law has pointed out the problem with this argument on his blog Forensic Science, Statistics & the Law.  In a blog post on July 26, Professor Kaye explains why Professor Obasogie is wrong on this point.  In his words:

The 150 or so matches were, in fact, mismatches. That is, they were partial matches that actually excluded every “matching” pair. Only if an analyst improperly ignored the nonmatching parts of the profiles or if these did not appear in a crime-scene sample could they be reported to match.

There is much more to Professor Kaye’s thorough and lucid explanation.  If you are interested in a real understanding of how DNA actually works, I strongly recommend Professor Kaye’s post.

In yesterday’s post, I discussed Maryland v. King.  Those arguments,  heard at the Court on February 26, considered whether a state should be permitted to take a DNA sample from every person arrested (not convicted — arrested) for a felony.  I asked in my post that we put questions of  individual privacy aside, and instead ask whether such wide sampling would be a good idea from a crime-solving point of view.  (Some experts do not think so, as discussed in the post.)

Today, let’s put the question of privacy back into the equation, because that appears to be what the Justices will do.

In his recap of the Feb. 26 argument, Scotusblog’s Lyle Denniston tells us that the key points were posed by two of the Court’s conservative justices.  According to Denniston, Justice Samuel Alito clearly favored the idea that law enforcement should be able to take these samples.  DNA sampling “is the 21st century fingerprint” Alito said at least twice.  According to his way of thinking, there is no constitutional difference (in terms of the degree of intrusion on individual privacy) between taking a fingerprint and taking a DNA sample.

The other pole of the argument was taken up by conservative icon Justice Antonin Scalia.  When the lawyer for the state of Maryland used a long list of cases solved through DNA testing to support her argument in support of the law, Justice Scalia reacted forcefully.  According to the National Law Journal:  “Well, that’s really good!” Scalia exploded. “I’ll bet if you conducted a lot of unreasonable searches and seizures, you’d get more convictions, too. That proves absolutely nothing.”  In other words, the question isn’t whether the state’s action solves cases; some methods of solving cases are simply not allowed under the Constitution, even if they could be proven to work better than others.  The question is whether the Constitution — in this case, the Fourth Amendment’s prohibition of unreasonable searches — allows the state to do what it wants to do.

During Tuesday’s argument, Justice Alito commented that King could be “the most important criminal procedure case this Court has had in decades.”  That will depend on how the Court decides the case, which it will do sometime before the end of June.  But one thing we do know:  the debate between law enforcement’s desire to use all the tools it can to fight crime and the Constitution’s protections of the individual against state intrusion will go on.

My  presentation Failed Evidence on January 31 at the University of Toledo College of Law — lively, well attended, and intense — featured a great question that I want to put to everyone.

One person in attendance was a man who is a police chief in Ohio.  He’s had a long and distinguished career; I had the great privilege of working with him some years ago, when I was a member of the University of Toledo faculty.    In one part of my presentation on Failed Evidence, I discussed the more than 300 cases since 1989 in which DNA identification has resulted in an exoneration.   In the Q & A after the talk, the chief asked a question about the 300-plus cases.  I’ll paraphrase: among those cases, he said, there would be some in which the DNA results disproved the conviction, but did not necessarily prove the defendant was not guilty.  This is because, he said, the absence of the defendant’s DNA may not support guilt, but it also does not necessarily prove innocence either.  (I’m hoping I understood his comment/question correctly and am conveying it clearly.) Was I prepared to admit that in at least some of the 300 cases, the defendants might indeed be guilty, even if the DNA had resulted in the defendant’s release and the dropping of charges?

I have had this question asked of me before, and heard it posed to others.  I gave my answer, but I would like very much to hear yours.  What do you think? Is the question correct, or is it based on certain assumptions that may not hold?  What would your answer to the question be?