Multiple Firearms Seized in Search Warrant 

January 3, 2025 – Stanislaus County Sheriff’s Office officials report that on December 16th, 2024, Sheriff's Detectives assigned to the Threat Assessment Unit received a tip from a concerned citizen regarding an individual who was posting disturbing material on social media. The citizen was concerned because the individual, who was their friend, recently began posting violent extremist and active shooter culture material. 

Sheriff's Detectives were able to identify the individual as Matthew Der. During the investigation, the reported information was verified, and a threat assessment was conducted. While no specific threat was identified, the Detectives took a proactive approach and petitioned the courts for a Gun Violence Restraining Order (GVRO) after discovering that Matthew had 4 handguns registered to him. The GVRO was approved, and a search warrant was obtained to collect the handguns. 

Thursday morning Investigators Threat Assessment Unit and Community Resource Unit from the Sheriff's Office contacted Matthew, served him with the GVRO, and then served a search warrant at his residence outside of Riverbank. During the search warrant, Investigators located a total of 5 handguns, 5 rifles, hundreds of rounds of ammunition, dozens of high-capacity rifle and handgun magazines, and body armor. Investigators recovered the 4 handguns that were registered to Matthew, but the other 6 weapons located were unregistered. Three of the rifles are classified as assault rifles under current California law and illegal to possess.

Matthew was arrested and booked in the Public Safety Center for possession of the 3 assault rifles.

We want to thank the reporting party for stepping up and making a report regarding the concerning behavior they observed. The Stanislaus County Sheriff's Office encourages the community to remember the saying, "If you see something, say something."

Source & photo: Stanislaus County Sheriff’s Office