General reply.
My ex-wife has a PhD in Criminology and has worked as a professor in that area for nearly twenty years. She is nationally recognized and is, frankly, brilliant. There is literally nothing in her education that would prepare her to commit a crime like this and leave no trace, or mastermind it, any better than most of us could attempt based on watching true-crime television shows. This suspect, as a first semester PhD student, likely has no great insight either. We all know you could wear a hazmat suit, cover your hair, wear gloves, etc. Leave your phone at home. Don't have your phone on you when you stake out the property. Don't be seen staking out the property.
Second, there are a lot of posts suggesting he should have ran after committing the crime (if he did it). I would suggest that would have gotten him caught even faster. Four people are murdered and a local student and teaching assistant disappears from his classes and his teaching duties? A 28-year-old male just vanishes at the exact time that everyone is on high alert and wondering who could have done it? Law enforcement would have been on him like white on rice. And a head start would probably not help him evade the law for too long.