The wife of a deputy U.S. marshal who shot and killed a man after a traffic dispute in Montgomery County last week tried to restrain her husband before he opened fire, according to a police affidavit filed in court.

But the deputy, Arthur L. Lloyd, 53, rebuffed his wife, saying, "I'm going to show him," then fired the first of four shots, the affidavit states.

The initial shot hit the victim, Ryan T. Stowers, 20, in the right leg during a confrontation between him and Lloyd in the parking lot of Mid-Pike Plaza, off Rockville Pike, shortly before 8:30 p.m. Oct. 28, according to police. Stowers was out of his vehicle at the time, as were Lloyd and his wife, according to the affidavit. Other court documents identify the wife as Wanda Guzman Lloyd, 29.

Police said Stowers, a Navy seaman, was killed by a subsequent shot, which struck him in the upper back after he had gotten back in his car and was driving away, according to police.

The incident apparently followed a traffic altercation on the pike between Stowers, who was alone in his Chevrolet Camaro, and Lloyd, who was with his wife and several small children in a sport-utility vehicle, according to police and witnesses. The two pulled into the parking area, got out and fought before Lloyd drew his weapon, police and witnesses said.

Police said they interviewed numerous witnesses. During the fight, "Lloyd sustained some injuries," the affidavit states. It does not say who threw the first punch. "As a result of the fight with Stowers," the affidavit states, Lloyd drew his weapon. "Lloyd's wife exited the vehicle and tried to restrain him," according to the affidavit, which does not say how she tried to do so.

After being shot in the leg, the affidavit states, Stowers screamed, "You just shot me!" Then he called 911 on his cell phone, according to the affidavit.

Lloyd ordered Stowers to get on the ground, but Stowers got in his car, the affidavit states. Lloyd told Stowers not to drive away and identified himself as a law enforcement officer, showing his badge and saying, "I'm a federal marshal," according to the affidavit.

Moments later, Lloyd fired three shots into Stowers's car as Stowers was driving away, according to police and a witness interviewed by The Washington Post. One of those shots struck Stowers in his upper back, killing him.

Lloyd, a 28-year member of the U.S. Marshals Service who was off-duty at the time of the shooting, was charged Tuesday with first-degree murder and other offenses. He is being held in the Montgomery jail pending a bond hearing tomorrow.

Stefanie Roemer, Lloyd's attorney, said her client "was acting reasonably in the course of duty." She said Stowers "was an individual who was in an agitated state who was clearly posing a danger to the officer and his family." She said Lloyd "was acting not only reasonably but in defense of himself and his family."

Lloyd suffered a black eye and a broken thumb in the fight with Stowers. Two law enforcement sources, speaking on condition of anonymity because the case is still under investigation, said Stowers punched Lloyd repeatedly and pulled his shirt over his head. Stowers beat up Lloyd "pretty badly," one source said.

After Lloyd showed his badge, Stowers said, "Show me your ID, show me your photo ID," the affidavit states. "I don't believe you. Show me an ID, something with a picture."

At the same time, the affidavit states, Lloyd was yelling "Get out of the car, or I'm going to shoot. If you leave, watch what's going to happen to you in the morning. You just hit a federal officer."

As Stowers drove past Lloyd, who was standing on the driver's side of Stowers's car, Lloyd fired three shots, the affidavit states.

Police said one bullet passed through the open driver's side window and hit Stowers in the upper back; the other two smashed the car's rear window and a taillight.

Arthur Lloyd, a deputy U.S. marshal for 28 years, told Stowers after their fight, "You just hit a federal officer." Ryan Stowers reentered his car after being shot in the leg and yelled at Lloyd to show him a photo ID.