A Criminal Court jury on Friday found Christopher Levi Parker guilty of first-degree murder in the slaying of Robbie McClure at a trailer in Hixson.
Judge Barry Steelman then sentenced Parker to life in prison.
He was convicted though two people who witnessed the shooting refused to testify against him.
One of them, Andrew Biro, had testified in General Sessions Court, and that testimony was played to the jury.
He said Parker had a beef with McClure and they went to his trailer home on Hixson Avenue off Norcross Road.
He said both Parker and McClure rose at the same time, then Parker shot him in the head.