On Wednesday night, about 200 people attended the vigil. The gathering became unruly when about half of them splintered off and marched to a nearby police precinct station house. After officers in riot gear set up a roadblock on Church Avenue, Mr. Gray’s sister Mahnefah tried to cross the street and was put into a police car. She was given a summons and released. Some of the protesters shouted, “That’s the sister,” then started throwing bottles when the police would not release her. Someone hurled a chair. Screams could be heard as skirmishes broke out on side streets.

For local residents, many of whom voiced skepticism about the official account, the situation surrounding Mr. Gray’s death was grimly familiar. Less than a year before, and only blocks away, a narcotics detective shot and killed an unarmed 23-year-old woman, Shantel Davis, as she tried to flee the police in a car that had been reported stolen at gunpoint, the police said at the time.

Vigils followed that shooting as well. But soon the rhythms of daily life returned, marked by what young men and women said was a daily backbeat of police stops.

“You try to put it out of your mind,” said Ms. Davis’s sister Crystal.

In interviews around East Flatbush, many spoke of a Police Department that, in its aggressive pursuit of gangs and informal criminal crews, had sown distrust, especially among young men and women, who feel that their encounters with officers often have racial overtones.

Image Kimani Gray

At a barbershop along Church Avenue, two men on Tuesday were discussing the recent shooting when an Asian delivery cyclist pulled onto the sidewalk across the street. “See that guy?” said Elverton Thomas, 39, a black man and telemarketer who was there for a haircut. “He can ride on the sidewalk. We can’t.”

His barber, Julian Clark, also black, concurred. Two years before, he said, an officer stopped him in front of the shop for sidewalk riding, and then arrested him after the officer said his identification had expired; he spent a day in custody sorting it out, he said.