You could very well be right. Maybe he wasn't thinking straight and didn't think of the consequences being even worse. It's possible. I just don't think so myself. Been wrong before! ( once) ha ha JkThat's a possibility as well, could have been any number of reason as far as we know.
But in this situation, I think it was not to leave a witness. Maybe a panic killing. I don't know if I believe he has escalated to this. I feel that he had bad intentions, but it got out of control when she fought back. I really think he didn't think she would fight as much as she did.
MOO