The 40th Precinct, though, remains one of a few areas where homicides have persisted, feeding off the isolation of poverty and turf rivalries among criminal crews that linger despite the neighborhood’s progress in undoing some of its history as an emblem of urban blight. In the neighborhoods that make up the precinct — Melrose, Mott Haven and Port Morris — nine people were murdered last year; the precinct recorded the biggest increase in the city in major crimes. This year, all three city police officers who have been shot were struck amid the precinct’s housing projects. They all survived.

To understand how and why killings continue in a city that has seen crime fall to historic lows, The New York Times is reporting this year on violence in the 40th Precinct, and documenting the story of each homicide.

Image Ms. Torres-Gonzalez. Her killing was the first of 2016 in the 40th Precinct.

A Neighborhood in Transition

Sixty years after the predominantly Irish area was transformed by blacks and Puerto Ricans moving into new housing projects, it now faces the specter of another overhaul as developers buy up once-industrial waterfront property for luxury towers.

But the vast tracts of public housing are not going away, and residents still speak of routines shaped by day-to-day violence whose victims they say are often ignored — among them undocumented immigrants, many from Mexico, who worry about coming forward to report crime. Homicides in the precinct reached 21 in 2011, after hovering between eight and 16 for a decade before that, and then dropped to 12 in 2012, eight in 2013 and seven in 2014 before rising again last year.

Roughly a third of the precinct’s 95,000 residents live in public housing, and data show that people who live in those buildings and on their edges are packed almost twice as densely as residents of the precinct over all. The 15th Congressional District, which includes the area, is the poorest in the United States.

“Housing and gangs,” said Robert K. Boyce, the Police Department’s chief of detectives, who led the 40th Precinct from 2000 to 2002. “Each housing development has its own little gang or crew.”