Stanislaus County Sheriff’s Office Seizes Firearms and Arrests Individual Following Threat Assessment
Photo Above: Stock Image
On December 16, 2024, detectives from the Stanislaus County Sheriff’s Office Threat Assessment Unit initiated an investigation following a tip from a concerned citizen regarding an individual posting violent extremist and active shooter-related material on social media. The reporting party, a friend of the individual, expressed concern over the nature of the posts, prompting law enforcement to act.
The investigation identified the individual as Matthew Der. Detectives verified the information and conducted a threat assessment. Although no specific threat was identified, detectives pursued a proactive approach by petitioning the courts for a Gun Violence Restraining Order (GVRO) after discovering Der had four registered handguns. The GVRO was granted, and a search warrant was obtained to confiscate the firearms.
Seized Items – Courtesy of Stanislaus County Sheriff’s Office
On the morning of January 2nd, investigators from the Threat Assessment Unit and Community Resource Unit contacted Der at his residence near Riverbank, serving both the GVRO and the search warrant. During the search, investigators seized a total of five handguns, five rifles, hundreds of rounds of ammunition, high-capacity magazines, and body armor. While the four registered handguns were recovered, six additional unregistered firearms were also found. Among the rifles seized, three were classified as assault rifles under California law and are prohibited.
Der was arrested and booked into the Stanislaus County Public Safety Center on charges of possessing the illegal assault rifles.
The Sheriff’s Office acknowledged the critical role of the reporting party in identifying the behavior and urged the community to remain vigilant, emphasizing the importance of the principle, “If you see something, say something.”
