Social media posts lead to arrest of Riverbank man for illegal firearms, assault weapons
A Riverbank man was arrested after the Stanislaus County Sheriff’s Office discovered a cache of illegal firearms at his residence.
The arrest came after a concerned citizen reported the man’s alarming social media posts, which included content promoting violent extremism and active shooter culture.
On Dec. 16, detectives assigned to the Threat Assessment Unit verified the content and conducted a threat assessment. Although no direct threats were identified, they discovered that Matthew Der had four handguns registered to his name.
Detectives petitioned the court for a Gun Violence Restraining Order, which was granted, allowing them to seize Der’s firearms. On Thursday morning, the Investigators Threat Assessment Unit and Community Resource Unit served Der the warrant at his residence outside of Riverbank.
During the search, investigators found a substantial arsenal: five handguns, five rifles, hundreds of rounds of ammunition, dozens of high-capacity magazines and body armor. While the four registered handguns were recovered, six additional weapons were unregistered, including three rifles classified as assault weapons under California law.
Der was arrested and booked into the Public Safety Center for possession of the three assault rifles.
The Stanislaus County Sheriff’s Office commended the reporting party for making the report.
“If you see something, say something,” the Sheriff’s Office wrote in a press release.
