A San Jose civilian community service officer, who briefly served as a sworn police officer, was arrested on suspicion of gun crimes last week after a FBI investigation linked him to social media posts advocating for killing cops and other hate speech on an alt-right website.

Denis Shevchenko, 40, of Gilroy, is facing misdemeanor charges for possession of a concealed firearm, possession of an assault weapon and possession of a concealed dirk or dagger; as well as a charge for storing a loaded handgun in his locker at the South San Jose substation of the Police Department, where he works at the community service officer program.

The gun crimes only came to light after the FBI San Francisco Bay Area division's Joint Terrorism Task Force informed San Jose police about Shevchenko's links to potentially threatening comments made on gab.com on May 24. The FBI was able to trace posts back to Shevchenko's IP address, police said.

Police did not specify what the posts said except that they were “of political nature involving violence and threats.”

The FBI informed SJPD on Oct. 14 and by that evening, officers had arrested Shevchenko while he was on duty at PayPal Park.

“The same day that we were made aware of these posts, the San Jose Police Department took immediate action to protect the community, and our employees,” San Jose Police Chief Anthony Mata said at a news conference Friday.

Officers got a search warrant for his residence, where they found nine firearms, one of which was an illegally modified AR-15-style rifle, Mata said.

The police chief said SJPD also took his electronics and other evidence to investigate any hate speech or threats Shevchenko may have made.

“These allegations are extremely serious and are being fully investigated to determine the extent of any criminal conduct by our employee, and the extent to which any others may be involved,” Mata said.

Shevchenko was arraigned Tuesday and is currently out of custody.

As a community service officer, he does not have police powers and is not allowed to be armed while on duty. At this time, he has been placed on a paid administrative leave pending results of the investigation by SJPD and the FBI, who are working in conjunction.

Mata said there has not been any indication so far that Shevchenko was going to act on threats of violence or that there are other officers involved, however that may change as authorities continue to investigate.

“We haven't dealt with this in years past, and now there's a growing presence of extremism in our country,” Mata said. “So, we're keeping up with the technology. A lot of these individuals post anonymously, so these are complex investigations.”

In 2020, some SJPD officers were linked to a private Facebook group filled with racist and bigoted comments, which drew lots of public scrutiny regarding officers' online threats.

Mata said his department has since implemented myriad measures to screen for hateful or extreme ideologies within the department, like social media screenings for potential officers and a psychological exam.

“I am extremely disappointed that an employee in our organization may have harbored and may have spread these hateful messages,” Mata said. “I strongly condemn extremist ideologies and hate, which have no place in this community and will not be tolerated at this department.”