This topic brings back some uncomfortable memories for me, seeing that I was at one point on the knife edge of actually hurting a person, and I can honestly say probably with enough force to kill them.
Well, when I first met my fiancée two years ago, she took the brave decision to tell me that she had been abused by her grandfather between the ages of 11-13. The details of which, I will not go into. After a year of us being together, she decided to go to the police and report him, as now she felt strong enough to go through interviews, trial etc.
At this point, I could see how scared she was of him, real fear of someone, she couldn't go to the local shop, as his house was right next to it, and whenever she saw him, she would start shaking, and at one point got hysterical when we walked into a corner shop, and he was in one of the isle's.
I had very dark thoughts at this point. I felt that if he simply stopped living, that my fiancée could go on and live a normal life, not worrying about him or jumping at loud noises as a side effect of her abuse. I thought about how to kill him clinically, without any remorse or pity. I felt nothing for him, only contempt in what he had done. Only one thing stopped my thoughts, after a few months of having them, and funnily enough, it was my fiancée:
"I hope he gets found guilty, so everyone can see him for the monster that he is, and I'll finally have my justice."
And that's what stopped my thoughts. I was foolish to think that murder was the answer, but when you are in a desperate situation, you are not thinking straight, and any idea, no matter how extreme, to help, sounds good. If I had gone ahead, I might have ended up in prison myself, and at worst, denied my fiancée her justice, by essentially helping the dirty fucker avoid his punishment, keeping his character intact. But I didn't, and now he's serving eight years in a "special" prison, to avoid getting a arse hole like a doughnut, or getting bashed six ways to hell by the lags at every opportunity. I've never told my fiancée about these thoughts and never will, as I don't want her to think of me being capable of something like murder, no mater how honourable I might have thought my actions were.
TL:DR Murder is never the answer, but sometimes, it may seem like it.