Unclear

The FBI defines a murder "cleared" if a suspect has been identified and arrested. But a murder can also be declared cleared through what's known as an "exceptional means." For example, if a suspect is dead, can't be extradited or prosecutors refuse to press charges.
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There's one problem with that. There is nothing on the FBI's page on Clearances, a page that the NPR article links to, that says that a prosecutor's refusal to press charges allows for a clearance by exceptional means. That page is from 2017, but the page from 2019, the most recent one, says the same thing. One of the criteria that must be met for a case to be cleared by exceptional means is:

Encountered a circumstance outside the control of law enforcement that prohibits the agency from arresting, charging, and prosecuting the offender.

A prosecutor declining to press charges wouldn't seem to be outside the control of law enforcement.

There's also the matter of a fairly obvious perverse incentive. If a case can be cleared when prosecutors refuse to press charges, why wouldn't police agencies arrest people who might fit some description or profile, refer them for prosecution, and then mark the case as cleared when the prosecutor declines due to lack of evidence. One would expect very high clearance rates this way. (Not that the current normal criteria don't inflate clearance rates somewhat... if someone "Turned over to the court for prosecution" counts for clearance of a case, the later acquittal of the suspect doesn't appear to matter.)

Not to say that a refusal to prosecute can't be a reason why a clearance by exceptional means would be granted. But it would seem that there would have to be something more at play than a prosecutor simply declining to press charges, since we expect prosecutors to decline to charge people when the case against them is very weak, or there are otherwise circumstances that lead prosecutors to be less confidence than police officers that they have the right person.

The criteria for case clearance is one of those things that likely only a small number of people outside of law enforcement or otherwise attached to or interested in the criminal justice system really pay attention to. So, if the public is going to be informed about the matter, it's important that media outlets describe it properly, because most people aren't going to have any other source of knowledge. I was actually familiar with the FBI's case clearance guidelines, so the NPR statement stood out for me when I saw it. Honestly, I suspect that I'm not the only one. I wouldn't be surprised to see a correction in the article tomorrow. But for now, the statement is dubious, perhaps because it's secondary to the human-interest story that drives the piece.