If the force the police used proved to be fatal then so be it. Fuck around and find out.
If you don't want to get kicked in the head by a policeman don't stab people and then refuse to give up your weapon. Simple. I believe that if it was my child, I believe that if they were mentally ill. If someone is stabbing people their threat needs to be made safe even if that results in their death.
Unfortunately as seems to be coming out about this person you can kill people, few years in prison then out to do it again so the public are undoubtedly safer if he was dead.