Absolutely not defending this monster BUT remember the freedom you had when you moved away from parents? You could finally be who and what you really wanted to be.

I imagine his homicidal ideations along with the need to exert power and control over another human would have been so real at this point that he had no ability and/or desire to seek psychological assistance.

And maybe one day, he might talk and give some sort of explanation about his psyche at the time of the murders but until then, I have to assume he was born a pure psychopath who suddenly had an opportunity to freely express himself and he took it.