Complex sentence: However, Miles manages to escape when Trager leaves him alone for a moment, and upon breaking free and locating the elevator key, Miles activates it and crushes Trager between floors inadvertently when he attempts to follow.
Split into simpler sentences: However, Miles manages to escape when Trager leaves him alone for a moment. After locating the elevator key and fleeing to the elevator, Miles activates it and crushes Trager between floors inadvertently when he attempts to follow.