N.Y.P.D. Commissioner James O’Neill Is Expected to Resign

James P. O’Neill, the New York City police commissioner who attempted to mend a racial divide between the Police Department and the public, was expected to step down from his position on Monday, ending a tumultuous three-year tenure as head of the country’s largest police force, two officials said.

Commissioner O’Neill, 62, initially set out to heal strained relations between the Police Department and black and Hispanic communities in a growing city of 8.6 million residents. His signature intervention, the department’s neighborhood policing program, was designed to build trust and respect between officers and civilians.

But his tenure was instead characterized by some of the department’s most fraught controversies. He is most likely to be remembered for firing a police officer who placed Eric Garner in a lethal chokehold five years earlier.

Commissioner O’Neill held the line on violent crime, securing the gains of previous commissioners and presiding over an era of low crime, with murder rates dipping to lows not seen since the 1950s.

He also took public stands aimed at redressing past controversies, apologizing to the L.G.B.T.Q. community for the department’s handling of the Stonewall uprising in 1969 and issuing a public apology to a woman who was maligned by police officials after she had been raped in Prospect Park.

The commissioner was expected to be replaced by Dermot F. Shea, the current chief of detectives, according to a City Hall official.

J. David Goodman and Jeffery C. Mays contributed reporting.