Mr. Santucci bequeathed to Mr. Brown one of the most rancorous cases then pending in the city’s courts. It involved murder charges against five New York City police officers that Mr. Santucci’s office had obtained from a grand jury weeks before in the death of a car-theft suspect. The office said that one officer had choked the man and that the four others had “acted in concert.” Witnesses said the officers had punched and kicked the man.

The officers contended that they had struggled to subdue the man, who they said was violently resisting arrest. Some legal experts called the murder charges against the four who were not accused of the choking prosecutorial overreach.

Mr. Brown agreed, dropping all charges against those four shortly after taking office. Moreover, he reduced the charges against the officer who allegedly did the choking to manslaughter and criminally negligent homicide, calling those charges more appropriate. The officer was acquitted of both counts at trial.

The family of the dead man, Federico Pereira, and his supporters were outraged, contending that Mr. Brown had made a political calculation that a more lenient stance toward the police would help his chances of winning a full term in a special election later in 1991.

Mr. Brown’s aides disputed that accusation, noting that he had become the front-runner when Mr. Cuomo gave him the interim appointment. He said his actions reflected the perspective of someone who had spent a decade as an appellate judge.

Mr. Brown easily defeated his Republican opponent in the election and was re-elected every four years afterward with multiparty backing, most recently in 2015, making him the longest-serving district attorney in Queens.

Years later, Mr. Brown found himself dealing with another emotionally charged case involving police action: the 2006 killing of a man, Sean Bell, and the wounding of two other men in a hail of 50 police bullets fired at their car — without justification, Mr. Brown’s office charged — during a chaotic confrontation outside a strip club in Jamaica, Queens.

Three detectives were tried on charges that included manslaughter and reckless endangerment. The detectives said that the car had hit one of them, and that they had believed that the men had a gun. No gun was found in the car. The wounded men said that they and Mr. Bell had been desperately trying to flee because they believed that the detectives, in plainclothes, were robbers.

Some critics of the police said that the incident was a vivid example of the kind of excessive force that they said the police routinely used against unarmed black men, even though two of the prosecuted detectives were also black.

In an interview with The New York Timesafterward, Mr. Brown, noting the challenges the case had posed to his office, said he had told his staff that the office had the respect of the police and the confidence of Queens residents and that he had wanted “to be certain that we come out of this investigation with that reputation intact.”

The detectives were acquitted at trial of all the charges. Critics of the prosecution contended that its trial tactics had significantly helped the defense. Mr. Brown responded that the decisions on tactics had been “appropriately made.”