NEW HAVEN

Shafiq Abdussabur’s creaky 1986 Mercedes rolls past the Gothic spires, the Urban Outfitters, Gourmet Heaven and the rest of the rarefied zone around Yale onto Dixwell Avenue and, bam, the world changes.

“That’s where they shot my nephew,” he says. He peers out at the Dixwell Mini-Market, in the heart of the Corridor, the city’s high-crime area. In the past two weeks, five black men were murdered over eight days. There have been 11 homicides in the city this year, 17 since October, 14 in the Corridor.

Tywan Turner wasn’t really the nephew of Mr. Abdussabur, a New Haven police officer who heads Ctribat Institute for Social Development, a gun violence prevention program that works with children in troubled New Haven neighborhoods, takes them camping in the summer, gives them a home beyond the streets. But Mr. Turner had been a beloved participant in the program, so his murder at age 19 felt like a death in the family. He had left a cookout at a friend’s house on Saturday, walked to the store for cigarettes and was shot at least four times. It was the second homicide that day.

“Awesome kid, a sweetheart, like my kids,” says Mr. Abdussabur, 43, who grew up in the neighborhood and ran track at the University of West Georgia. “Respectful, handsome, nice smile. Not a fighting kid, very laid back, very smart. Someone was in a dispute with his brother and retaliated against him.”