steve_mcnairNASHVILLE, Tenn. — Federal agents have arrested a convicted murderer for allegedly providing the gun later used to kill ex-NFL quarterback Steve McNair.

Adrian J. Gilliam Jr., 33, of LaVergne, Tenn., was arrested by agents of the Bureau of Alcohol, Tobacco, Firearms, and Explosives.

A criminal complaint unsealed Friday in Nashville says that Gilliam — who was convicted of murder and attempted armed robbery in 1993 in Florida — admitted he sold the gun to the woman who later shot McNair.

McNair was shot to death on July 4 at his condo by his 20-year-old mistress, Sahel Kazemi, who then turned the gun on herself.

The complaint, signed by ATF agent Mickey French, charges Gilliam with illegally possessing a firearm, which he is barred from doing as a felon.

Detectives traced the gun, a 9 mm Bryco/Jennings, to its 2002 sale at a pawn shop, according to the complaint. Gilliam eventually bought it from an individual for $100 about a year or year and a half ago. Investigators said Gilliam told them he bought the gun for protection after his home was burglarized, and police reports indicate he did report a burglary about the time of the gun purchase.

According to court documents, Gilliam admitted to detectives he sold the gun to Kazemi for $100.

Federal prosecutors in Nashville planned to announce the case at a press conference later Friday.

Police announced in a news conference last week that Kazemi purchased “a fully loaded nine millimeter pistol from a private individual” who met her in the parking lot of the mall where she worked at a Dave & Busters restaurant.

Kazemi met the person when she was trying to sell her car. She mentioned to him that she was looking to buy a gun and he told her he had one for sale, police said. The sale took place two days before McNair’s shooting, outside the restaurant where Kazemi worked and first met McNair.

Authorities believe McNair was asleep when Kazemi put the pistol to his head and pulled the trigger. She put two more slugs into his chest and a fourth bullet into the other side of his head before shooting herself.

McNair, a married father of four, walked away from the NFL last year. “Air McNair” was known as a gutsy quarterback who played through serious injuries and led his Tennessee Titans to a Super Bowl.

Though the gun sale in question did not involve a licensed gun dealer, the ATF recently warned all gun dealers in Tennessee that they must still comply with federal gun laws despite a new state law aimed at easing such requirements for weapons manufactured and sold in-state.

Associated Press Writers Harry Weber in Atlanta and Devlin Barrett in Washington, D.C. contributed to this report.