Updated

Police have charged a Woodbridge man with murder, accusing him of fatally shooting a retired federal agent who was out walking his dog.

Prince William County Police charged 25-year-old Aric Alexander Smith with first-degree murder and armed robbery.

Killed in Wednesday night's slaying was 55-year-old Gregory L. Holley Sr., also of Woodbridge. The Bureau of Alcohol, Tobacco and Firearms said Holley was an ATF agent in Chicago, Atlanta and Washington and was the ATF's special agent in charge in Detroit. He concluded his career as a deputy assistant inspector general for the Department of Treasury, from which he retired in 2009.

Police say Smith was arrested fleeing from the scene by an off-duty police officer. They say Smith was found in possession of personal property belonging to Holley.

Police do not believe the two knew each other and say the gun used in the slaying was reported stolen last week.

Holley's family said he was an active volunteer at his church, New Life Anointed Ministries International.

"Greg's life work was about fighting violent crime, and unfortunately it was violent crime that took his life," the family said in a statement.