A Fairfax County assistant prosecutor said yesterday that her office is investigating whether a 22-year-old Reston man charged with involuntary manslaughter in a traffic death last December was stopped by police several hours before the accident and released without being charged.

Assistant Fairfax prosecutor Lorraine Nordlund said yesterday that testimony given in Fairfax General District Court on Tuesday led her to believe that Roger O. Simmers was drunk when he was stopped several hours before the accident that killed Lisa Bates.

Bates, a 17-year-old South Lakes High School cheerleader, died Dec. 8 when the car in which she was riding was struck broadside by a car allegedly driven by Simmers.

Nordlund said her office does not know which police agency stopped Simmers, exactly where the stop occurred or why the officer initially pulled Simmers over.

A few hours later, the accident occurred at King's Lake and Rosedown drives in Reston. Simmers was subsequently arrested at the Access emergency medical care facility, where he was taken for treatment by county fire rescue units who had been called to the home of his girlfriend.

Simmers, who is charged with felony hit and run in addition to involuntary manslaughter, showed a blood alcohol level of .12 percent at the time of the arrest; the legal intoxication level is .10 percent. Simmers was not charged with driving while intoxicated because the involuntary manslaughter charge covers the lesser DWI charge.

Edward Sharp, who was a companion of Simmers on the evening the accident occurred, testified Tuesday that the pair had been stopped by a police officer on the George Washington Memorial Parkway several hours before the accident, according to Nordlund.

Sharp testified at a hearing at which the charges against Simmers were ordered bound over for consideration by a grand jury on March 18.

Based on what Sharp told police and prosecutors, Nordlund said she believes Simmers was drunk at the time of that initial stop, which occurred at least 90 minutes before the accident.

Simmers was not cited at the time of the initial stop, Nordlund said, but the officer did order him to move beer from the passenger compartment of the car to the trunk and Sharp took over driving. Simmers resumed driving when the pair left a Tysons Corner bar, she said.

"I don't think people should jump to the conclusion that because there was a stop, he was drunk," Simmers' attorney Barry Schneiderman said yesterday.

"I dispute any suggestion or characterization that the policeman [making the initial stop] was wrong or derelict in what he did," he said. "The fact that he was not cited for anything means he was not in any apparent violation of any statute."