In the early hours of Sunday morning, the manhunt for a gunman who killed two Brown University students seemed to be over. The police had detained a “person of interest” and lifted a shelter-in-place advisory that had been in effect while the gunman was at large.
By late evening, though, the authorities were backpedaling. The man, whose name had leaked to the news media by then, was released.
So what is a person of interest, anyway?
It is not an official legal term. But it can be used to describe someone who the authorities believe has important information about a crime — a witness, perhaps, or an accomplice. More often, a person of interest is really a suspect whom the police are not ready to call a suspect, for legal reasons or because some of the evidence has yet to be nailed down.
Andrew Birrell, the president of the National Association of Criminal Defense Lawyers, said he is always wary of the term person of interest because it “feels like an effort to dilute the amount of evidence you have to have to acquire the person of interest.”
The fact that the shelter-in-place order was lifted when the man in Rhode Island was apprehended was “an absolute sign that they were sure that he is the person responsible,” said Maria Haberfeld, a policing expert at John Jay College of Criminal Justice.
She added that as it turned out, this was “an error in judgment.”
After a short video believed to show the gunman was released, the F.B.I. received a tip that led to the man, the authorities said. Gov. Daniel McKee of Rhode Island referred to him as “a suspect.”
But Chief Oscar Perez of the Providence Police Department was more circumspect, declining to answer questions such as where the man had been caught and whether a weapon had been found. When the chief was asked about the man “in custody,” he was tapped on the shoulder by someone who whispered, “Custody is not the right word.” Chief Perez corrected the reporter, using the word “detained.”
“Those words, and how we choose those words when we’re talking about an investigation, matter,” said Rhode Island’s attorney general, Peter F. Neronha, at a news conference announcing that the man had been released. “And what it means here is that certainly there was some degree of evidence that pointed to this individual. But that evidence needed to be corroborated and confirmed.”
A person can be detained for questioning based on a reasonable belief that they are armed and dangerous. Someone who has been detained by the police more than briefly may have the freedom to leave if they are not placed under arrest (though research shows they are unlikely to exercise it).
If a person is in custody, on the other hand, they must be advised of their Miranda rights, including their right to remain silent. It generally means they have been arrested, which requires probable cause.
The early hours following a shooting, especially a high-profile one, can be full of misinformation and false reports. After the conservative activist Charlie Kirk was gunned down during an appearance on a college campus this fall, two people were questioned and released, while the F.B.I. director announced, incorrectly, that a suspect was in custody.
In Providence, the authorities defended their shift in direction, saying it was just the way investigations go. That is likely to be cold comfort for the person of interest, whose name and photograph were widely disseminated while news reporters published facts about his work history, mental health and social media posts.
Premature identifications can ruin lives, as in the case of Richard A. Jewell, a security guard who helped shepherd dozens of people out of danger before a bombing at the Atlanta Olympics in 1996, but then was named as a suspect in a news report that did not cite a source.
It was years before the actual bomber, Eric Rudolph, was caught, and by then, he had committed three more bombings.
In Rhode Island on Monday, it became clear how quickly law enforcement officials can change direction when the clues lead them elsewhere. Mr. Neronha said that the person who had been held in connection with the shooting on Sunday was “not a person of interest at all at this point.”