A convicted murderer has pleaded guilty to selling the gun that was used to kill ex-NFL quarterback Steve McNair.

Federal court documents filed Friday show that Adrian Gilliam of La Vergne, Tenn., admitted that he sold a loaded 9 mm semiautomatic pistol to McNair’s mistress for $100.

Nashville police have said the woman, Sahel Kazemi, used the weapon to kill McNair and then herself on July 4.

Police said the 19-year-old Kazemi met Gilliam while she was trying to sell her car and told him she was looking to buy a gun. Gilliam was arrested about two weeks after the shootings.

Gilliam, who is 33, faces up to 10 years in prison and a $250,000 fine. According to prosecutors, he was convicted in 1993 in Florida for murder and attempted armed robbery.