I know a family who is going through the same hell.
Grandpa (pillar of the community, deacon of the church, Bible thumper) was a child molestor and managed to molest two generations of kids. To this day nobody in that family is allowed to admit it, but his victims live with this hell everyday.
If this were my family, I probably wouldn't have shot him, I'd PAY someone to hurt him really bad, though. Had it been my daughter, niece, or anyone close to me, he'd have been beaten to a pulp everytime he looked at a girl the wrong way.
I like your approach.
It's not deadly vigilantism, it's just a nasty, painful object lesson every time he screws up.
[kinda like negative reinforcement therapy]...:)