A 10-year veteran Los Angeles police officer is now at the center of the department’s growing cadet program scandal.

Robert Cain, 31, was taken into custody Thursday, the Daily Breeze reports. He’s accused of having an unlawful sexual relationship with a 15-year-old cadet who was allegedly involved in stealing police cruisers, Chief Charlie Beck said during a news conference at police headquarters in downtown Los Angeles.

Cain was an “equipment room operator,” responsible for overseeing equipment at the department’s 77th Street Division, where the theft of three LAPD patrol vehicles occurred last week, Beck said.

Investigators zeroed in on communications between Cain and the female cadet after analyzing her phone, according to Beck.

“Text messages were found that we thought could indicate inappropriate behavior,” Beck said.

The Los Angeles Times reports that a cache of more than 100 firearms, including modified AR-style rifles were found at Cain's home Friday. 

A neighbor, who asked not to be identified for fear of repercussions, told The Times that Cain has an extensive gun collection and likes to build and modify his own AR-15 semi-automatic rifles. Cain would sometimes invite others to participate in the weapons projects, including fellow law enforcement officers, the neighbor said.