Journalists covering the fatal shooting of a security officer assigned to Denver’s Regional Transportation District are reporting that the suspect was a homegrown extremist who appeared on a database of potential terrorists.

Joshua Cummings, 37, a Texas native, was arrested soon after witnesses say he approached RTD contract security guard Scott Von Lanken from behind late Tuesday night and shot him in the head. According to KUSA, police said the attack was “completely unprovoked” and wondered if Von Lanken, 56, was targeted because of his dark blue uniform.

Cummings, described by an acquaintance as “a crazy man” who “creeped everybody out,” reportedly appears in a database of potential terrorists. reports that Cummings enlisted in the U.S. Army in July 1997 and eventually reached the rank of sergeant in July 2002. He opened a jiu jitsu academy in Texas in 2015 and moved to the Denver area last fall.