I think you're right about the pre-planning. I'll bet he had some "accident" planned when he went to North Carolina. Then he could pretend to "withdraw" from medical school, and that would be the end of that.
Lori stumbled on the truth a few weeks too early.
The attorney for Mark Hacking gives lawyers the bad name they have. The guy is obviously guilty. Does he want this murderer back on the street.
But wasn't Mark planning to go on ahead of Lori by several weeks? I read that in one account. It seems to me that he planned to "go on ahead to NC" and instead of waiting there for Lori to appear, just disappear. It would have been easy. But she found out the truth. And confronted him. And he killed her.