An attorney for Arthur Miles, the youth charged in April's ambush slaying of a pizza deliveryman in Prince George's County, said in court yesterday that Miles is responsible for the death. But he argued that the killing was unintentional and did not amount to a murder.

In his opening statement in Miles's Circuit Court trial, defense lawyer David M. Simpson conceded that his 16-year-old client and another suspect lured Domino's Pizza employee Carl A. Krogmann, 25, to a vacant house in Largo, where they planned to rob him. And Simpson said the bullet that killed Krogmann in the April 7 holdup came from a gun held by Miles.

But he also told the jury in Judge Jacob S. Levin's courtroom that the pistol went off accidentally, and that Miles, at worst, is guilty of involuntary manslaughter, not first-degree murder.

"He's the cause of Carl Krogmann's death," Simpson said of Miles, who police say admitted his role in the killing after being arrested two days later.

"I'm not going to dispute that," Simpson said. "He's not going to dispute that. It's the extent of his culpability that's in question."

Involuntary manslaughter is punishable by up to 10 years in prison.

Prosecutor Jeffrey Harding, however, told the jurors in his opening statement that under the state's felony-murder statute, if a victim dies accidentally or otherwise during the commission of a felony, the applicable charge is murder.

"An accident is not a defense to felony murder," Harding told the jury shortly after it was empaneled. "I cannot tell you that enough."

Miles and the other suspect, Roland H. Jeeter, 18, were arrested April 9. The case gained wide media attention a few weeks later, when District Court Judge Gerard Devlin set bond for Miles at $75,000, allowing him to be released pending the outcome of the trial.

Angered by the move, Krogmann's relatives mounted a much-publicized campaign for Devlin's ouster. The effort included a petition drive, a news conference by a family friend, Sen. Paul Simon (D-Ill.), a national television appearance by Krogmann's parents and a march on Devlin's home and the state House by the Guardian Angels, a self-styled crime-fighting group.

Judge Levin revoked Miles's bond in May. But Maryland's Court of Special Appeals ordered it reinstated last month, saying Levin's decision appeared to have been influenced by public opinion.

Miles remains free on bond during his trial.

Jeeter, scheduled for trial next month, is being held at the Prince George's County Correctional Center.

In testimony yesterday, Jennifer Ramsay, 21, who was Krogmann's girlfriend, told the jury that she accompanied Krogmann when he left Domino's to deliver a pizza to a house in the 11000 block of Mount Ludentia Way in Largo.

Ramsay, waiting in the car, said she heard the gunshot from the house's front porch and watched Krogmann run from the house to the street. She said she drove until she caught up with him.

"At that point, I knew he'd been hit, because he was throwing up blood all over my windshield," Ramsay testified, haltingly.

Krogmann had been shot once in the chest.

Ramsay said she tried to hold him upright, to stop him from choking on his own blood.

"Then," she said, "a couple of minutes later, before the paramedics ever came, he just died."