Stephen A. Carr worked aggressively, but patiently, to try to slow down the cars that flew past his house in the Burke area of Fairfax County. Most of his neighbors applauded his help, and earlier this year a speed hump was installed in front of his house.

But David A. Patton evidently was not a fan. In June, court and police records show, Patton angrily confronted Carr about the speed hump outside Carr's house. Patton was charged with misdemeanor assault. His trial was set for Thursday.

On Sunday night, police say, Patton went further. Witnesses told police he burst into Carr's house, tied up Carr and his girlfriend and, when Carr struggled, fatally shot him in the head, court records allege.

Patton, 44, was arrested a short time later in Carr's back yard and charged with murder.

Neighbors said Carr, 48, was single, well-known and liked in the Orange Hunt neighborhood, just off Sydenstricker Road. He worked for the Federal Aviation Administration in its Washington headquarters, spokeswoman Diane Spitalieri said, but she declined to say what he did or how long he worked for the agency.

Carr's next-door neighbor on Field Master Drive, Willis Palmer, said Carr "brought my paper to my door every morning. He helped people with blowing leaves and cleaning their gutters. He was very active around here."

But because of his activism over the speed hump, Palmer said, Carr was also a source of controversy.

"People would come by at night and honk their horn," Palmer said. "I told him he should be careful. He said he could take care of whatever anyone did to him."

Carr had worked through the office of County Supervisor Pat S. Herrity (R-Springfield) to get a speed hump installed almost in front of his house. Herrity said Carr began his campaign in May 2008, a process that involves neighborhood consent and traffic engineering studies. The speed hump was approved in January, county records show, and installed soon after.

"He was a guy who really cared about his community," Herrity said. He "cared about the kids and their safety." Herrity noted that Field Master Drive is near Orange Hunt Elementary School.

"It's a shame this sort of thing happened," Herrity said.

On June 11, Patton showed up at Carr's house shortly before 9 p.m., Fairfax police officer Bud Walker said. Carr told police that he was trying to back his vehicle into his driveway and that Patton had pulled in behind him to block his access, Walker said.

The two men had a "verbal altercation," Walker said, then Patton moved his car out of Carr's way. Carr began backing into his driveway, but Patton walked over and began berating Carr, according to a handwritten complaint Carr filed the next day. Palmer said Carr told him the dispute was about the speed hump.

Carr wrote that Patton "struck my back window, side windows, then reached in my passenger window and grabbed my arm." Carr added that both he and Patton called 911, with Patton asking for an ambulance because he claimed Carr had struck him with his vehicle.

Police arrived but could not arrest anyone because they did not witness the clash. So Carr went to a magistrate the next day, records show. Walker said the magistrate consulted with the officer who handled the case and then issued a warrant for Patton. Patton was arrested July 6.

His attorney in the case, Joseph J. McCarthy, declined to comment Monday.

The case was pending when Patton burst into Carr's house through the front door shortly before 10 p.m. Sunday, while Carr and his girlfriend were watching television, the girlfriend told police, according to court records.

Patton ordered Carr and his girlfriend to the floor and tied their hands with zip ties, according to a search warrant affidavit written by Robert A. Bond, a Fairfax homicide detective. When Carr tried to get out of his ties, a struggle ensued, and Patton shot and killed Carr, police said.

The girlfriend ran out of the two-story house, and Patton followed her and forced her back inside, Bond wrote.

While they were inside, the affidavit states, a man who also lives in the house with Carr arrived home. Patton ordered him to lie on the ground, too, but then was momentarily distracted, and the roommate ran out of the house with Patton in pursuit, Bond wrote.

Meanwhile, Carr's girlfriend ran upstairs and dialed 911. Police responded quickly and sealed off the neighborhood. When they closed in, they found Patton in the back yard of Carr's house carrying a backpack containing zip ties and a revolver, the affidavit says.

Police searched Patton's townhouse on Conservation Way, a short distance from Carr's home, early Monday. Records show they found a box for a .22-caliber Ruger handgun, and a "deputy badge." Police declined to describe the badge.

Patton was arraigned Monday morning and ordered held without bond. The Fairfax public defender was appointed to represent him. A woman who answered the door at his townhouse on Conservation Way declined to comment Monday.