Wednesday, the nation was peppered with breathless, if thinly sourced, reports of a shocking link between two very different, seemingly unrelated crimes: a match between DNA samples lifted from the CD player owned by and found near the corpse of slain Julliard student Sarah Fox in 2004 and ones taken from a chain used to open a gate in a free-subway-rides stunt backed by Occupy Wall Street in March. OWS MURDER LINK, blared the New York Post cover.

But just as quickly as the story had arrived, it fizzled, undone by multiple reports that the DNA belonged not to a suspected killer, but rather to a NYPD lab technician.

It was a high-profile embarrassment for New York State’s use of DNA samples that also raised new questions about the NYPD’s much-criticized treatment of Occupy Wall Street. (Occupy was also in the news Wednesday after a group marching from Philadelphia briefly returned to Zuccotti Park) Perhaps foremost among those questions: How was the apparent error missed, and the Occupy-murder angle pushed to the press, when the ME’s office contends that it has records of all its workers’ DNA to avoid just this sort of false match?

In March, Gov. Andrew Cuomo signed a law greatly expanding the state’s databank, which now collects DNA from anyone convicted of any crime, even a misdemeanor (the sole exception is for those without criminal records convicted of public possession of small amounts of marijuana)—giving the state one of the nation’s most extensive and intrusive DNA policies. At the time, critics, including The New York Times, charged that the law was unfairly tilted in favor of prosecuting alleged criminals rather than exonerating falsely convicted ones.

In one sense, the current investigation is a separate issue—no one is arguing that police don’t have the right to collect evidence from a crime scene and test it for DNA, which the law views in a far different light than the more invasive process of collecting DNA from a human being. So the NYPD could have tested the chain even before the new law went into effect. But this incident still fits firmly into the broader set of concerns civil liberties groups have about the manner in which New York deals with DNA evidence.

“There are plenty of entirely innocent reasons and explanations as to why one’s DNA may turn up at a crime scene,” said Robert Perry, Legislative Director of the New York Civil Liberties Union, “but in the popular imagination and even in the minds of some law enforcement professionals, DNA evidence takes on almost magical properties. Meaning its very presence at a crime scene may come to signify guilt.”

Perry and his organization have long argued that policies like New York’s, intended to build vast collections of DNA samples from a wide swatch of the population, are much more likely to lead to matches—and that this isn’t a good thing. A match, they argue, doesn’t automatically indicate culpability, because, as Perry explained, people tend to underestimate “how frequently human error can enter into the collection and analysis of DNA.” Matches occurring due to issues like cross-contamination or degraded samples that get misinterpreted happen “with alarming frequency, and it’s not fully appreciated by the public or law enforcement professionals,” he said. Perry pointed to the work of researchers like William C. Thompson (PDF), who have called into question the infallible manner in which DNA evidence is viewed by many laypeople and even law enforcement pros.

As for this particular match, there’s also a question of selective enforcement. If this door-chaining, part of a wildcat push by New York’s rather radical Transit Workers Union, hadn’t been connected to Occupy Wall Street, a group against which the NYPD has been engaged in a long, ugly struggle, would the city have gone through the hassle of lifting DNA evidence from the chain—especially given that it was likely to be contaminated by anyone else who touched it?

The NYPD’s press office declined to answer The Daily Beast’s questions about why DNA was collected from the chain. But David Kaye, a law professor at Penn State and the author of The Double Helix and the Law of Evidence, said the department’s tactics in this case stood out.

“What’s interesting is taking [the DNA] from a chain that so many people could have touched and then running that through the database of crime-scene samples ... and finding a match,” he said. “I guess that’s creative.”

“They’re either very committed to finding clues, no matter how weak, or they’re out to get a group of people.”