A couple of them.

One, I met when we were both five years old, and I knew then he would end up in prison. He helped beat someone to death when he was 19 and went to prison.

Another I met when I was a child and he was an adult. I knew he wasn't quite right, but I had no idea how bad it was. As a teenager, I had an encounter with him that almost turned violent. He later raped both his daughters and went to prison.