A New York City police sergeant who killed a mentally ill woman wielding a baseball bat ignored his training to isolate her and instead rushed to take her down, provoking the confrontation that led to her death, a prosecutor told a judge Tuesday at the opening of the officer’s trial on murder and manslaughter charges

In a Bronx courtroom packed with police officers and parishioners from the woman’s church, the prosecutor, Newton Mendys, said that four police officers had already talked the woman, Deborah Danner, into putting down a pair of scissors and were trying to coax her out of her apartment, when the sergeant, Hugh Barry, arrived and took charge.

“He made a bad situation worse,” Mr. Mendys said. “He created a situation that was rushed, hurried, careless, reckless, chaotic and ultimately tragic.”

Within minutes of arriving, Sergeant Barry led the other officers in a failed attempt to tackle Ms. Danner, who was 66, overweight and in the grip of a psychotic episode. Ms. Danner retreated into her bedroom and grabbed a baseball bat, Mr. Mendys said. Sergeant Barry drew his gun and ordered her to drop it. As she shifted her weight to swing it, he shot her twice, the prosecutor said.