He was the perp. The little girl was the victim.
Exactly.
I see 2 victims here, the little girl was the primary one of course, her father was the other one. The molester made the father kill him.
Regardless of "common knowledge", it is not pleasant to most people to kill another person, no matter the circumstances.
Don't take me the wrong way, it is sometimes absolutely called for and an appropriate response, as in this case.
I'll be 67 on the 29 the of this month and probably a bit long in the tooth to be beating someone to death, unless he was an incredible weakling, so if I witness such a heinous act as this father did, I'd be compelled to kill him with a gun.
Kudos to this great dad for defending his little daughter.