A former deputy U.S. marshal who killed a young Navy seaman in a road rage incident last year at a Rockville shopping plaza was sentenced yesterday to 15 years in prison.

Arthur L. Lloyd, 54, who was convicted in June of voluntary manslaughter in the Oct. 29 shooting of Ryan T. Stowers, probably will serve about 11 years before he is eligible for parole, prosecutors said.

Calling the shooting "an enormous tragedy" for both families, Montgomery County Circuit Court Judge Ann S. Harrington tailored a sentence that satisfied neither side completely. She went beyond state guidelines calling for a five- to 10-year sentence, but she declined to impose the maximum 35-year term requested by prosecutors.

Holding a collection of family photographs, Tricia Stowers told the court she believes Lloyd should serve the same amount of time she had been allowed with her son before his life was cut short.

"Your honor, this whole time I've had to listen to the defense's version of what happened, I never hear, 'I'm sorry.' I never hear, 'I was wrong,' " Stowers said. "That's not going to bring Ryan back, and putting Mr. Lloyd in jail will never bring Ryan back. But he needs to realize that he was wrong. He needs to sit there and think about it every day, every day for at least 20 years. Twenty years -- that's what I had with my son."

When it was his turn to speak, Lloyd asked the family to forgive him. Then, in remarks that drifted over several subjects, he placed some blame for the deadly encounter on Stowers's intoxication. He said that all law enforcement officers have been on edge in the post-Sept. 11 world and that he became fearful for himself and his family when Stowers followed him into the shopping plaza.

He claimed that he had no choice but to take action against a driver who made "racially profane" remarks and menaced him and his family. Lloyd is black; Stowers was white.

"Just between me and God, and to the family, especially the mother, and all the brothers and sisters, I have to ask forgiveness. And I have to ask forgiveness because a young man lost his life," Lloyd told the court.

The shooting occurred at the Mid-Pike Plaza in front of dozens of horrified witnesses, many of whom were shopping with children for Halloween costumes. That was why Lloyd, off duty and accompanied by his wife and five young children, headed to the shopping plaza in his black SUV. Then he encountered Stowers. A state toxicology report determined later that Stowers had a blood alcohol concentration nearly three times Maryland's legal driving limit.

Their traffic dispute became a fistfight. Dozens of shoppers dialed 911 on cell phones. Witnesses testified that, as Lloyd's wife tried to hold him back, Lloyd went to his vehicle for his .40-caliber Glock service weapon, vowing: "I'm going to show him."

Lloyd shot Stowers in the leg, saying he feared for his life and wanted only to disable a crazed adversary. Lloyd said he felt that his life was in danger when Stowers attempted to drive away in his red Camaro. Lloyd fired three shots into Stowers's car, one of which clipped Stowers's aorta.

Witnesses -- some of whom returned to court yesterday to address the judge -- said Lloyd looked more like an enraged motorist waving a gun around than a trained law enforcement officer. They said they, too, had been afraid.

Eugenia Hull, a Silver Spring woman who was buying Halloween costumes with her two boys, recalled holding her arms out to shield them, later realizing how absurd the gesture was.

"I had no way to protect my children from this man with a gun," said Hull, 44.

Arthur L. Lloyd sits as his case is argued before Montgomery County Circuit Court Judge Ann S. Harrington. Seated in the front row are the parents of Ryan T. Stowers. Lloyd shot their son during a fight in a Rockville shopping plaza.