Investigators said the link between Nathan Cheatham and Adam Price provided a possible motive for the slayings.

The 27-year-old Cheatham had a history of drug abuse and emotional problems and had recently stopped taking medication prescribed by a psychiatrist, authorities told the Richmond (Va.) Times-Dispatch.

Cheatham was said to have grown highly agitated, concerned that Price was talking to police about their involvement in the drive-by shooting at a Great Falls, Va., home. No one was hurt.

On Christmas morning, according to police, Cheatham shot his 53-year-old mother several times outside their McLean, Va., home, then drove to Price's home where he shot him, Price's mother and a visiting family friend. Cheatham then shot himself in the head.