An Alexandria Circuit Court grand jury declined yesterday to indict a city police officer who, officials said, accidentally shot and killed his 12-year-old stepson during a game of cops and robbers.

Shortly after the grand jury reached its decision, Alexandria Commonwealth's Attorney John E. Kloch said he has no plans to proceed further with the case.

"If they grand jurors chose not to indict, I have no further plans to proceed," Kloch said. "I think it's clear it was an accidental shooting."

Officer William R. Trotti, who has been on administrative leave since the July 5 incident, will return to full-time duties while the department continues its review of the shooting, Police Chief Charles T. Strobel said yesterday.

The Alexandria Commonwealth's Attorney's office yesterday asked the grand jury to consider whether to indict Trotti for involuntary manslaughter, but after reviewing facts about the case, the six-member panel declined to return an indictment.

The decision to place Trotti, 32, on administrative leave is the normal procedure when an officer discharges his service revolver, Strobel said yesterday.

"I understand he's (Trotti) involved in some medical attention as a result of the incident," Strobel said yesterday. "We're awaiting to get a medical clearance from his doctor and return him to full status."

The incident occurred while Trotti's stepson, John Joseph Staus, 12, was holding a toy gun and playing cops and robbers with Trotti in the living room of the family's 10th floor apartment on Duke Street in Alexandria.

Trotti, an 11-year veteran of the Alexandria police force, was standing nearby, inspecting a .38-caliber service revolver that he had recently carried while on duty, police said.

As the boy imitated the sound of a gun firing, Trotti turned toward him and the service revolver discharged, according to police. A single, hollow-point bullet struck John Staus in the chest.

Police and the commonwealth's attorney's office have refused to comment on the details of the shooting or the conclusions of the police investigation. An autopsy was to be conducted by the Northern Virginia Medical Examiner's Office to determine whether the bullet that struck Staus ricocheted or entered his body directly.