I made the first comment about reasoning this out. I didn't intend to offend anyone, we are generating a lot of questions and answers here. But we're coming at it from different angles and I'm having a hard time keeping track of what suppositions have been debunked.
We can't get into the motivation of the killer because obviously, that's beyond most of us here. But we can use reason to make predictions about what he/she will do next based upon probabilities. And we can deduce lots of things by the way the LEO's act and what they say.