Acting on a tip from a concerned citizen, Stanislaus County Sheriff's Detectives seized multiple firearms, including three classified as assault rifles under California law, from an individual posting violent extremist content on social media. According to a statement from the Stanislaus County Sheriff's Office, the tip was prompted by changes in the social media posts of the individual, identified as Matthew Der, that raised concerns.
The Threat Assessment Unit responded by verifying the reported information and conducting a threat assessment. While no specific threat was identified during the investigation, detectives decided to take proactive steps. They filed for a Gun Violence Restraining Order (GVRO) against Matthew, who had four handguns registered in his name. After securing the GVRO and a search warrant, deputies conducted a search at Matthew's residence, located outside Riverbank.
The search uncovered more than what was initially expected from the GVRO. In addition to the four registered handguns, deputies found an unregistered handgun, five rifles, hundreds of rounds of ammunition, multiple high-capacity magazines, and body armor. Matthew was found to possess six unregistered firearms, including three rifles that are illegal under state law. He was arrested and charged with possession of illegal assault rifles and booked into the Public Safety Center.
