FRESNO, Calif. (AP) — A Fresno County sheriff's deputy who shot a sergeant to death will stand trial for involuntary manslaughter.

The Fresno Bee reports that a judge ordered trial Thursday for Jared Mullis.

Prosecutors say Mullis's gun went off and shot Sgt. Rod Lucas last year as they horsed around in an office near Fresno Yosemite International Airport.

Details of the incident remain unclear but the judge says it appears that Mullis pointed a loaded gun at Lucas before it went off.

The defense has suggested Lucas may have dropped a gun that went off, killing him. Prosecutors reject that idea.

Mullis is on paid leave from the Sheriff's Department. He could face four years in prison if convicted.