A police officer will be prosecuted on manslaughter charges in the shooting death of Ramarley Graham, an 18-year-old who was killed by a single police bullet in his bathroom after a team of narcotics officers broke into his Bronx home, three people briefed on the charges said Monday.

The officer, Richard Haste, a four-year veteran of the Police Department, is expected to turn himself in on Wednesday for arraignment, the people said. A grand jury recently voted to indict Officer Haste, 30, on charges of first- and second-degree manslaughter, but the indictment has not been unsealed, they said. It was unclear if he would face additional charges.

This is the first time a New York City police officer has been indicted on a charge stemming from an on-duty shooting since three detectives were charged in March 2007 in the death of Sean Bell, a 23-year-old who was leaving a strip club hours before he was to be wed. The detectives were later acquitted. (Another officer, Rafael Lora, was indicted in December 2007 for an off-duty shooting that killed the driver of a minivan.)

Mr. Graham was unarmed when he was shot.

The Feb. 2 shooting occurred shortly after two other police officers radioed colleagues and said they believed Mr. Graham was carrying a gun in his waistband as he walked toward his home in the Wakefield section of the Bronx. Based on that observation, Officer Haste rushed to the scene and broke into the apartment where Mr. Graham lived. He confronted the young man in the bathroom and fired a single, fatal shot, the police have said.