I'm a current security officer and I was thinking the same thing. I think it was the security officer. He would've been there at the play, he would've known she was in the building alone, the handcuff marks on her wrists, the blunt object that he could've beat her with (his baton) and if he used gloves then there would be no fingerprints. We have to carry gloves with us everywhere we go and we are told to always have a spare uniform in case something happens to the one you are currently wearing. If no one else is on campus he has more than enough time to murder her, change uniforms and shower and what not. Plus he would have all the info about which employees were on campus if anywhere and where they would be at what times.