Cassie Randolph's war with Colton Underwood is now in the hands of law enforcement ... TMZ's learned she filed a report claiming he put a tracking device on her car.
Law enforcement sources tell TMZ ... Cassie went to the L.A. County Sheriff's Department Wednesday night to file a complaint about the allegation she first made against the 'Bachelor' star in her request for a restraining order against him.
Cassie's lawyer, Bryan Freedman, tells TMZ ... "It was her intention to first, try and work through this process privately in a manner that gives both her and Colton safety, security and respect.