To understand what drives such violence, The New York Times is documenting each homicide in the 40th Precinct this year. It recorded nine murders in the precinct last year, the 11th highest total among the city’s 77 precincts. It had recorded five as of Saturday, more than all but two other precincts.

Police officers in the South Bronx are trying to break through the shame and fear that often keep victims from reporting abuse, visiting them repeatedly even if they slam the door.

The killing of Ms. Saavedra, who lived in a private, five-story walk-up building, emerged from the same swirl of jealousy, mental instability and silence that makes it difficult for investigators across the city to anticipate domestic violence.

Ms. Saavedra told relatives that she was staying with Mr. Uribe for the sake of their children, despite the years of marital problems. There were no reports to the police of domestic abuse, though she filed for a temporary order of protection with Bronx Family Court on Jan. 29, after Mr. Uribe cut himself and banged on her door; the order was never served.

Lincoln Medical and Mental Health Center, where the police brought Mr. Uribe after that episode, released him after less than two days, reflecting the difficulty in decoding risk factors.

At a recent public safety meeting, Sgt. Michael J. LoPuzzo, the commander of the 40th Precinct detective squad, expressed regret that Ms. Saavedra had never told officers she feared for her safety. “Maybe we could have prevented that,” he said.

Image Ms. Saavedra on her wedding day in Mexico. She was 15 when she married Mr. Uribe.

Even in retrospect, relatives struggled to pinpoint the moment a tumultuous marriage had turned murderous.