DNA evidence has become the gold standard of a criminal prosecution: Find it, type it and match it and a suspect is either transformed into a guilty party or exonerated. We forget, however, that DNA evidence does not speak. It remains circumstantial evidence. At most, DNA evidence permits a fact finder to draw an inference that the presence of a person's DNA at a crime scene means that the person was there at the time the crime was committed. That's it!
Consider the unsolved case of Suzanne Jovin. The 21-year-old Yale University student was found stabbed to death in an affluent residential neighborhood in New Haven in 1998. Her throat was slashed and she had been stabbed repeatedly in the back.
Lawmen announced that the DNA of another person had been retrieved from beneath a fingernail on her left hand. The stranger's DNA was there as a result of Ms. Jovin's close quarter struggle with her killer, lawmen told the world. Identify the source of the DNA and there's your killer.
The state tested the DNA of nearly 50 suspects, and failed to find a match. The case remains open. So far as the world knows, the state is no closer to solving the case now than it was a decade ago.
Except for the following: We now know the identity of the person whose DNA matches that found beneath the fingernail of Ms. Jovin. The man's name is Kitti Settachatgul. He is a retired state worker who once was suspended from his job of taking money he should never have accepted. Where was Mr. Settachatgul the night Ms. Jovin was murdered? Is he able now to construct an alibi for his whereabouts one discreet night a decade ago? He know lives in Thailand, after retiring from state service.
Ms. Settachatgul is not a suspect in the crime, however. He is not a suspect because although his DNA matches that allegedly taken from beneath the fingernail of Ms. Jovin, the state has constructed an innocent explanation for the presence of his DNA: You see, Mr. Settachatgul worked in the state DNA lab responsible for identifying, extracting and typing Ms. Jovin's DNA. The state's working theory is that Mr. Settachatgul's DNA is associated with crime because of sloppy police work: Mr. Settachatgul contaminated the DNA sample by careless handling of the evidence.
The limits of DNA evidence are at once on display. Had the DNA matched that of one of the 50 or so suspects whose DNA had previously been taken, there is little doubt but that a warrant would have been issued for the arrest of the matching party. Woe to the unlucky defendant in such a case. DNA is a talisman in the criminal court: it sets men free and sends men to their death with the algorithmic calm of a metronome. Indeed, in Connecticut, the state's Innocence Project has declared open love and adoration for the state's forensic crime lab: state and defense work under terms of an inquisitorial vow that looks askance at the adversarial process. DNA is regarded as magic.
But there is no magic in the Jovin case. Instead, there are new questions. Were their epithelial cells present beneath the fingernail of Ms. Jovin? These are skin cells, easily shed, and bearing DNA identifying the source of the cells. If so, was the density of those cells sufficient to support an inference that they were deposited under Ms. Jovin's skin during a struggle, rather than during the routine handling of evidence by a careless laboratory technician?
How did the State conclude that foreign DNA was beneath Ms. Jovin's nail? When was this determination made? Why did it take eight-plus years to figure out that the DNA sample matched a lab employee? And, perhaps most telling of all, just how did law enforcement decide to rule out Mr. Settachatgul as a suspect?
"[A]ll along we knew that the DNA evidence when only relevant when we knew who it belonged to," said the prosecutor responsible for investigating the case. "Now we know it is irrelevant."
The logic defies me. More needs to be known than that the suspect DNA was a lab worker. Had the DNA belonged to one of Ms. Jovin's professors, that professor would have faced a myriad of questions. What questions has the lab worker faced?
I realize how farcical the suggestion that the lab worker did it sounds. I raise the issue here not because I have any reason to suspect his guilt, but to hold in relief both the power and limits of DNA evidence. When viewed through a lens of suspicion, the evidence damns. Remove that lens, and all the evidence shows is mere presence.
Sadly, this example of poor laboratory work will now reopen the investigation of all those folks who were ruled out as a result of the assumption that foreign DNA under Ms. Jovin's fingernail belonged to that of the killer. This powerful piece of circumstantial evidence has been destroyed. It is back to square one for the Jovin family, and for all those whose lives were scrutinized in the weeks and months following the murder.
The case also raises important questions for the criminal defense bar in any case involving DNA: Should the defense be entitled as a matter of right to testing to determine whether DNA retrieved at a crime scene matches that of any of the folks who handled the evidence, including first responders, evidence officers and lab technicians?
Chain of custody evidence is sometimes treated as the step-child of trial. The Jovin case reminds us that great injustices can be built upon fatal and unchallenged assumptions. Unless, of course, the lab technician really did commit the crime. And, of course, that's a possibility the state seems unwilling even to consider in the troubling case of Suzanne Jovin.