Yesterday I made up a story that might be taken as excusing wicked behavior. It was about a local man who killed a child and injured two women while shooting at random vehicles. The man really did shoot into traffic and kill a child. The part I made up was the story of his life, and that might be taken as my saying, "You poor put-upon murderer. I understand. it's alright."
It's been my experience, for about as long as I've been conscious of the news, that people who try to understand vicious behavior are trying to excuse it. "The bully comes from a broken home," etc.
It's certainly true that there's a large area of intersection between understanding and compassion, but, with me at least, the impulse to understand comes from a desire to protect myself by accurately understanding what's going on.