I can't really admit to being an expert on this subject. There are still some people out there that I have yet to get my head around. But I'm working on it.
You can forgive almost everyone. No matter what heinous crime they have committed, what vile injustice or harm they may have caused, there is still hope. Here are the steps to successful recourse.
1. For all of this to work, the accused must truly feel sorry for their action(s). This is the trickiest of all the steps. Even if they don't show complete remorse over what they did, as long as you believe that one day they will understand the gravity of their actions, then they are salvageable.
2. You must understand the accused's motives and reasons for their actions. Not everything is their fault. Their upbringing, culture and peers affect how the accused acts. Not everyone is as strong as you would like them to be. Sometimes they really don't know any better. Don't fault them for that.
3. Having realized that it is not entirely their fault, show no hatred or anger towards the accused. Do not retaliate. Offer a smile and the accused will be closer to forgiveness.
4. When you feel that the time is right and there aren't too many people around, go right ahead. If they apologize first, accept graciously. If they do not, approach the accused and offer your friendship.
Realize that life is too short to stay mad for too long. Having enemies has no real benefit. If you can find the strength to forgive, sometimes this strength will pass on to someone else. Set an example. Take charge.
Everyone has someone they wish they had the strength to forgive. Reach out and do it. Today.