My (uninformed) guess at this time is that he’s a self-loathing poofter and could not deal with it. As far as him being pre-med, I bet his grades were in the crapper.
I read that he was suspended at least once.
I heard this morning that the police think the motive was MONEY. Fox News called his dad’s dentist practice and the receptionist said that he was too busy to come to the phone.