He met his wife, Kathleen, while both were recruits commuting to the Police Academy from the same Long Island town. As Chief Boyce recalled, somewhat ruefully, it was his wife who made the first homicide arrest of the two: “She pulled a .357 out of a guy’s waistband,” said Chief Boyce. “It turns out he had just murdered someone in Central Park with the gun.”

Chief Boyce was jealous.

“Extremely,” he said, laughing. She retired after the birth of the couple’s second child, after about eight years on the job.

In his lengthy career, Chief Boyce has not escaped the kind of scrutiny that at one point or another confronts many who rise to the highest levels of the department. An undercover detective, Zaher Zahrey, whom Mr. Boyce investigated while assigned to the Internal Affairs Bureau, filed suit after a federal jury in 1997 acquitted the detective of charges he assisted a drug gang in robberies, including one that resulted in a killing. The city fought the suit until 2009, when it reached a settlement of $750,001, plus $1.5 million in lawyers’ fees. Mr. Zahrey had named Mr. Boyce in the lawsuit, claiming the police and prosecutors had manufactured a false case against him.

A police spokesman did not answer questions left for him about the case.

Mr. Boyce rose to chief of detectives in February 2014, soon after Mr. de Blasio named Mr. Bratton commissioner. Chief Boyce said he did not know Mr. Bratton personally in the 1990s, when Mr. Boyce was “a mere sergeant” and Mr. Bratton was on his first tour as commissioner.

“Bratton said, ‘Look, I want the chief of detectives to talk,’ ” said Stephen Davis, the department’s top spokesman. “He said, ‘My chief of detectives is going to have to be comfortable and engaged.’ ”

Chief Boyce said he learned the importance of public speaking as a precinct commander, when he was expected to appear frequently before community groups and answer questions. It was good training for the kind of leader Mr. Bratton was looking for when he took the reins again at 1 Police Plaza in January 2014. “Always be prepared,” Chief Boyce said.

That preparation begins before dawn each day in his Long Island home, as he holds BlackBerry in hand. After some weight training, Chief Boyce is met by a police driver around 6 a.m. and reviews overnight case summaries on the drive to Police Headquarters in Manhattan. He usually briefs Mr. Bratton by midmorning. He is not shy about calling squad rooms directly.