From what I have read many murders happen by "normal" people - no psychopathy or anything is necessary. And a big problem seems to be rigidity in thought.

While I agree that controlling emotions is essential, gracefully dealing with them in the first place is also very important. Emotional outbursts seem like singular events while in reality they are build-ups that happen over long stretches of time. Maybe a more intuitive example is amok runs at schools. Counter-intuitively these are usually done by people who seem calm - cholerics are less likely to do amok runs.

FWIW reading also through the Wikipedia page, there was already a restraining order a year before.