A lawyer for another, Abdula R. Greene, who represented Ethan Philips, called the district attorney’s statement “a little bit of a smear on their character.”

But Ken Montgomery, a lawyer for Denzel Murray, another of the teenagers, did not find fault with the choice of words. “I think that is a way, from a policy and social standpoint, to say, ‘Young men should exercise a little bit better judgment in dealing with certain things,’ but what they did didn’t rise to criminality,” Mr. Montgomery said. “I would agree, in a sense, that we live in a country and a world where we have a lot of unhealthy ideas of what appropriate sexual relationships are.”

Mr. Thompson’s decision was a pivotal, if not entirely surprising, turn in a case that dominated news headlines and roiled New York City.

The police were initially criticized by some community leaders as waiting too long to alert the public to the report of the rape — the police released surveillance video of the suspects two days after the alleged attack — and Mayor Bill de Blasio and Police Commissioner William J. Bratton said officials should have alerted residents sooner.

Yet from early on, inconsistencies and other disclosures made it clear the case would be an uphill battle for Mr. Thompson, who called for “justice for the victim” but also made clear the case demanded a careful, thorough investigation.

Four of the teenagers arrested last month — Mr. Murray, 14; Mr. Philips, 15; Travis Beckford, 17; and Mr. Brown, 18 — were released after prosecutors did not file indictments within six days of their arrests, as would have been required to keep them detained pending a trial. Shaquell Cooper, 15, who was also charged in the case, is currently being held in jail on assault charges stemming from an episode in October 2015, officials said.

Despite the fear stoked by the initial reports, or the relief that followed the arrests, the case was always complicated. Moments after the mayor said the public should have been alerted more quickly, Robert K. Boyce, the Police Department’s chief of detectives, illustrated just how tangled the case was already becoming.