Do you think it's emotion or anger or ego/inferiority complex? I thought if he did do it he's probably a psychopathic personality, and this has been my opinion thus far, but your point is quite valid. You would almost think this is a crime of passion. Very hard to tell.
I agree, the crime of passion theory is one I have been entertaining too, since someone suggested it recently (Tinkerbel?)
It seems very clear to me, as I follow the threads on here, and the news headlines, that the motivating factors for 'murders' these days seem to be either jealousy and passion, or drugs.