A former federal agent walking his dog in his quiet Woodbridge neighborhood was gunned down Wednesday evening in what authorities called a random robbery gone wrong.

Police quickly arrested a suspect after a neighbor reported the sound of four gunshots. Officers said they do not think that Gregory Lee Holley’s career at the Bureau of Alcohol, Tobacco, Firearms and Explosives had anything to do with the shooting, which occurred about 9:40 p.m. on Wertz Drive. They also said they do not think Holley knew the man accused of attacking him. Police identified the suspect as Aric A. Smith, 25, of Bogner Drive in Woodbridge.

Police charged Smith with first-degree murder, armed robbery and using a firearm in commission of a felony, according to a news release. He is being held without bond, and a court date has been scheduled for June 19.

Smith was arrested after a brief struggle with an off-duty Prince William officer, Lt. Carlos Robles, who was in the area and chased the suspect on nearby Cardinal Drive, police said. Robles was in uniform while working a private security job when he heard the call on his radio, according to the county police.

Holley, 55, was pronounced dead at the scene, according to police.

Aric Alexander Smith, 25, of the 3700 block of Bogner Drive was charged with first-degree murder, armed robbery and using a firearm in commission of a felony, (Prince William County police)

He was often seen walking his dog on Wertz Lane, neighbors said. The neighborhood of small homes with neatly trimmed lawns and hedges is generally a safe, uneventful place, neighbors said.

Many who live there are current or former members of the military or law enforcement, said a neighbor, Darren Lee, 48.

“Having a shooting this close [to home] for no purpose — it’s ridiculous,” Lee said.

Holley began a federal career at the Internal Revenue Service and later became a special agent in Chicago and then Detroit, according to ATF.

In 2002, he was appointed to lead the ATF office in Detroit, according to the agency.

He worked on major cases, including the agency’s church arson task force, ATF said. He was also a retired Army officer.

Family members said in a statement that, given Holley’s line of work, they had prepared for the worst.

“This is something loved ones try to prepare for, but never expect to have to deal with,” said the statement, which was provided by ATF. “Greg’s life work was about fighting violent crime, and unfortunately it was violent crime that took his life.”

In 2005, Holley had gone to work for the Treasury Department’s inspector general for tax administration. He retired from the agency in 2009, according to the ATF statement.

His post-government life was on full display the day after the shooting at his Colonial-style red-brick home as members of the New Life Anointed Ministries International church in Woodbridge and family members streamed in with bags full of groceries. Holley had served in volunteer positions since March 2006 “with a smile and a kind word,” the family statement said, and took a staff position as the church’s chief financial officer after he retired from government work.

“Greg spent his life helping others and was well liked and respected. . . . He will be greatly missed by all who knew him,” the statement said.