There are also problems with the way DNA evidence is interpreted and presented to juries. In 2008, John Puckett — a California man in his 70s with a sexual assault record — was accused of a 1972 killing, after a trawl of the state database partially linked his DNA to crime scene evidence. As in the Anderson case, Mr. Puckett was identified and implicated primarily by this evidence. Jurors — told that there was only a one-in-1.1 million chance that this DNA match was pure coincidence — convicted him. He is now serving a life sentence.

But that one-in-1.1 million figure is misleading, according to two different expert committees, one convened by the F.B.I., the other by the National Research Council. It reflects the chance of a coincidental match in relation to the size of the general population (assuming that the suspect is the only one examined and is not related to the real culprit). Instead of the general population, we should be looking at only the number of profiles in the DNA database. Taking the size of the database into account in Mr. Puckett’s case (and, again, assuming the real culprit’s profile is not in the database) would have led to a dramatic change in the estimate, to one in three.

One juror was asked whether this figure would have affected the jury’s deliberations. “Of course it would have changed things,” he told reporters. “It would have changed a lot of things.”

DNA forensics is an invaluable tool for law enforcement. But it is most useful when it corroborates other evidence pointing to a suspect, or when used to determine whether any two individual samples match, like in the exonerations pursued by the Innocence Project.

But when the government gets into the business of warehousing millions of DNA profiles to seek “cold hits” as the primary basis for prosecutions, much more oversight by and accountability to the public is warranted. For far too long, we have allowed the myth of DNA infallibility to chip away at our skepticism of government’s prosecutorial power, undoubtedly leading to untold injustices.

In the Anderson case, thankfully, prosecutors acknowledged the obvious: their suspect could not have been in two places at once. But he was dangerously close to being on his way to death row because of that speck of DNA. That one piece of evidence — obtained from a technology with known limitations, and susceptible to human error and prosecutorial misuse — might mistakenly lead to execution at the hands of the state should send chills down every one of our spines. The next Lukis Anderson could be you. Better hope your alibi is as well documented as his.