Wiesenthal describes a dying Nazi soldier asking him for forgiveness for murdering Jews, which he does not grant. He then has fifty-three distinguished people tell us how they would respond to such a request.
Three other, more recent books, come to mind which have understanding the enemy and/or forgiveness as its theme. One is, Revenge: A Story of Hope (2003) by Laura Blumenfeld. Her father was shot by the PLO and survived and she sought revenge.
Not by the Sword: How the Love of a Cantor and His Family Transformed a Klansman (2012) by Watterson, is about how a Jewish cantor changes the life of a white supremacist by offering him friendship.
And a book I recently read is called The True American: Murder and Mercy in Texas (2015) by Giridharadas. It's about white trash shooting what he thinks are Arabs after the WTC attack on 9/11 and the one victim who survives, a Bangladeshi, forgiving him and working hard to prevent his execution.
Lots of food for thought here about who has the right to forgive and whether forgiveness and understanding are always positive qualities. Is there a G-dly standard for forgiveness?