I came across an article about Jim McCloskey of Centurion Ministries. He works to free prisoners who were falsely convicted. I love these kinds of innocence projects (the best-known ones involving DNA analysis), for they help the neediest and correct injustice.
As described on his website:
"The primary mission of Centurion Ministries is to vindicate and free from prison those who are completely innocent of the crimes for which they have been unjustly convicted and imprisoned for life or death. We also assist our clients, once they are freed, with reintegration into society on a self-reliant basis."
Without any formal training as a private investigator, why would he devote his life to doing this? "He started attending church again. The lessons McCloskey heard in the sermons “compelled one to serve others, and the only person I had been serving was myself.”"
He quit a lucrative job, went to seminary, and one thing led to another and now he's doing this.