It took a Pima County jury less than an hour Friday to convict a 22-year-old Tucson man of first-degree murder.

Victor "Lucky Charms" Lizardi was convicted of shooting Michael Smith, 43, to death as Smith napped on Aug. 14, 2011. He will be sentenced to life with or without the possibility of release by Superior Court Judge Teresa Godoy on April 15.

Smith's girlfriend, Donna Carter, testified earlier this week that she and Smith came home from a casino to find their roommates with Lizardi and Paul Hoiland.

She later caught Lizardi showing a gun to Hoiland, and she demanded he leave, Smith said.

As Hoiland escorted Lizardi to the door, Carter testified, she went into her roommates' bedroom. Moments later, she heard a gunshot.

As she ran out of the room, she bumped into Lizardi coming out of the bathroom adjoining her bedroom.

She found Smith on the bed where he'd been napping, his mouth full of blood, struggling to breathe.

He was pronounced dead at the scene, and Lizardi was arrested three days later.

Jurors were not told, but Lizardi is suspected of killing another man with the same gun during an armed robbery two days after he killed Smith.

Francisco Pereida, 24, was found mortally wounded near West Mabel Street and North 14th Avenue just after midnight Aug. 16, 2011. His car was reported missing and was found abandoned the next day.

Lizardi is scheduled to go to trial in the Pereida case April 16.