A detective with the U.S. Marshals Service was charged yesterday in the fatal shooting of his wife, hours after her body was found in an upstairs bedroom of their Loudoun County home, authorities said.

John Ludwig dialed 911 at 8:38 a.m. and said his wife was dead, Loudoun Sheriff Stephen O. Simpson said. Ludwig, a 17-year member of the Marshals Service, was taken into custody minutes later when authorities arrived at the Ashburn home, Simpson said.

Ludwig, 51, was charged in the afternoon with the first-degree murder of Karen M. Ludwig, 38, Simpson said. The sheriff said several shots had been fired, but he declined to give a possible motive for the slaying.

"He has been cooperative with our investigators and has been talking," Simpson said. Authorities said only that Ludwig told investigators that his wife was shot with a revolver after a domestic dispute and that he provided a "full account of what occurred in the home."

Simpson and his deputies spent much of the day waiting for approval of warrants that would allow them to search the couple's home in the 42800 block of Hollywood Park Place and their three vehicles, including a Chevrolet SUV that is owned by the Marshals Service. The home's red door remained open in the interim, and two deputies guarded the entrance. At 3:30 p.m., the warrants arrived, and gloved investigators entered the house to process the crime scene and remove Karen Ludwig's body.

Don Hines, a Marshals Service spokesman, said that John Ludwig joined the agency in March 1988 and that he is a criminal investigator. He said that his "status is being reviewed" but that no immediate administrative action was taken against him.

It was the fourth homicide in Loudoun this year and the second in Ashburn, a community of 50,000 residents about 30 miles west of Washington.

In March, a Loudoun sheriff's deputy shot and killed an Ashburn man after the man fired a weapon twice and seemed prepared to shoot again, moments after authorities were called to his townhouse because the man had fought with his girlfriend. And last year, a 15-year-old was shot to death in an Ashburn house by his 17-year-old friend, who later pleaded guilty to involuntary manslaughter.

Standing in their yards and in the wide, partially shaded streets, neighbors of the Ludwigs watched as crime scene tape was strung around the perimeter and uniformed sheriff's deputies drove in and out of the neighborhood.

Mike McCullough, 46, sat with his wife on their sloping lawn with an unobstructed view of the crime scene across the street. He called the slaying "bizarre, something straight out of a movie."

"You see this on the news all the time and you hear neighbors saying that the man who was arrested was such a nice guy, and I just never really believed it. But now here we're saying the same things, because he really was just a super-friendly guy," McCullough said. "We're in shock, I suppose, because it just doesn't seem real."

Others said Ludwig, a motorcyclist who owns three or four Harley-Davidsons, was never unkind or aloof. He always waved and said hello, said Bill Meetre, 42, who returned home from work yesterday afternoon to find his neighborhood crowded with police vehicles and media trucks.

McCullough said the Ludwigs hadn't been married long, maybe a year or two. Both had prior marriages, with children who are grown or living with another parent.

He said Ludwig was a police officer in Maryland before he joined the Marshals Service.

Every weekend, he and several of his biker friends would meet for long rides. Afterward, rows of motorcycles, with their shiny chrome reflecting the sunlight, would line the street in front of Ludwig's house, McCullough said, adding that he rode with the group a few times.

"We keep saying to ourselves that he really didn't do that because it just doesn't click," McCullough said. "It's just very sad."

Staff researcher Bobbye Pratt contributed to this report.

Loudoun County sheriff's deputies and members of the U.S. Marshals Service wait across from the Ludwigs' home in Ashburn for search warrants to arrive.Bill Meetre, with stepdaughter Ashly Robinson, says he returned home from work to find his neighborhood crowded with police and reporters.