its extremely sad. but it is hard to say.
the boy was beating his sister and cousin in a wheel chair. im gonna get beat up bad on here over this one......but I am the type that does not believe in the saying "if you kill a killer there are still the same amount of killers in the world" I look at it as a threat to the safety and well being of the honest and harmless members of society.
if the boy was a threat to society and a person that is not a threat to random innocent people......then I have no problem with him being removed from society. at the same time....if the dad was mentally unstable, as sad as that would be, then that doesn't change the fact that he is a danger to the safety and well being of law biding citizens...so he should be dealt with accordingly (not necessarily killed)
ex. if bob were to see ted rape someone......and kill them....or maybe viciously beat young children on a regular basis or something to that effect....and bob took ted out but was not a danger to good decent people.....bob provided a service to society. if bob is put away...the only ones served and protected by the law....are the rapist, murderers, and childe beaters.