James Malec was found guilty of voluntary manslaughter Thursday in the shooting of his stepson Justin Eilers last Christmas in Canyon County, Idaho, according to Idahostatesman.com.

Malec, 48, a former deputy sheriff, faces up to 15 years in prison and is expected to be sentenced in October, said the report. Prosecutors had sought a heavier conviction for second-degree murder.

A former Iowa State middle linebacker, the well-liked Eilers was a member of the Miletich Martial Arts team and fought for the UFC and EliteXC heavyweight titles in 2005 and 2008.

"Of course, nothing can bring Justin back, so there was no way this trial was going to turn out positive for those of us who cared about him,” said Eilers’ manager, Monte Cox, in an email to Sherdog.com Thursday. “And even though Malec was not found guilty of the more serious offense, I am relieved to know that he will be punished for what he did. As a former officer, I'm sure his time in prison will be far from comfortable."

Eilers was shot once in the chest with a large caliber handgun during a domestic dispute in Malec and Eilers’ mother’s home. He was pronounced dead at the scene after emergency medical technicians could not revive him with CPR. Eilers was 30.

Canyon County Coroner Vicki DeGeus-Morris confirmed that the single shot had punctured Eilers’ lung before it exited his back.

An argument between Eilers and an ex-girlfriend, who had an 8-year-old son together, broke out earlier that night and she had left the residence, attending officer Capt. Dana Maxfield told Sherdog.com last December.

Tensions continued in the kitchen between Eilers and Malec, said Maxfield, who also verified that both men had consumed alcohol that evening.

“[Eilers] was verbally challenging Malec,” said Maxfield.

Eilers was shot standing in the doorway adjoining the kitchen and the living room and fell back into the living area.

Malec’s defense team argued the ex-officer had acted in self-defense, as Eilers had threatened to kill him.

"Never lose sight of the fact that Justin tried to make a living by pummeling people into submission," defense attorney Gordon Petrie told the court, according to the report.

Eilers’ mother and Malec’s wife, Gwen Moore, witnessed the shooting and testified that Eilers’ had been backing away from Malec when he was shot.