I personally know 3 murderers. Met them all in space of just a year as homeless.

Two ex-professional criminals who killed other criminals back in the 90", and one guy who killed someone in a pub brawl that went wrong.

Those people are relatively normal and can be 100% rehabilitated.

I also know a guy who was forced to watch execution while a teenager - he on the other hand is mentally badly damaged 2 decades later.

Those guys are far less psychotic and toxic than many corporate leaders I met in my career.

I'm from Central Europe.