person who was apparently angry with him, his longtime girlfriend, a fellow student, 22-year-old lilly mesias. >> i do remember quite a few fights between the two of them where he'd be very upset, either hurt or mad at her. i don't know exactly what would happen. it was just they would have problems and you could tell. >> investigators found a voice mail from lilly to michael left at 8:30 that morning. >> she had left a message on michael's cell phone indicating that they were having problems and that she was done with their relationship. >> was it possible that lilly went to michael's apartment afterwards and there was an altercation? >> at that point, combined with the fact that it seemed like michael may have known the person who did this to him, she was initially a suspect. >> but lilly had an alibi. she was working at her part-time job on the morning of the murder and was eliminated as a suspect. >> she was very forthcoming. she was willing to give us a statement, willing to allow a search of her apartment, willing to allow us a search of her vehicle. >> michael's sister stephanie provid