DENVER (AP) — Police in Denver are investigating after a box of human heads was stolen from a freight company's truck this week. The Denver Police Department said in an email on Saturday that the human remains were being transported for medical research purposes. Investigators believe someone broke into the parked truck that had the box inside it between Wednesday afternoon and Thursday morning. Denver Police asked anyone who finds the blue-and-white box marked with a label saying "Exempt Human Specimen" to call police. No arrests had been made as of Saturday afternoon.