Earlier this year, the CASE Team received a tip and launched an investigation into a person who allegedly obtained Glock conversion switches. When installed, these switches allow the pistol to fire in a full automatic mode. These switches are considered machine guns, which are illegal.
CASE later obtained a search warrant for the suspect and his residence. On Thursday, June 20, 2019, the CASE Team executed the search warrant at the suspect’s residence in Foster City.
CASE recovered the following from the residence:
- Glock converter switches (4)
- 5.56 caliber AR-15 style assault rifles (3)
- 5.56 caliber machine gun with an attached silencer and grenade launcher
- 9mm assault pistol (2)
- 37mm incendiary rounds (2)
- Large capacity magazines (23)
CASE arrested 41-year-old Joseph Holmes of Foster City without incident. He was arrested for possession of a machine gun, possession of an assault rifle, manufacturing an assault rifle, possession of a silencer, possession of a destructive device, illegal transfer of a firearm, importation of large capacity magazines and possession of an explosive agent. The investigation will be forwarded to the Contra Costa D.A.’s Office for prosecution.
CASE (Contra Costa County Anti-Violence Support Effort) is a joint effort by the Office of the Sheriff, California Department of Justice, California Highway Patrol, Bureau of Alcohol, Tobacco, Firearms and Explosives, Pittsburg Police Department, and Probation Officers from the Contra Costa County Probation Department. CASE was created in November 2011 as a collaborative effort to reduce violent crimes in Contra Costa, especially those related to illegal firearms.
Information released by the Contra Costa County Office of the Sheriff