Criminal Minds - Episode 3.19 - Tabula Rasa

A young man is in prison as a convicted killer. A female corrections officer is very sympathetic and feels sorry for him and becomes a victim when he takes advantage of her kind nature. The man's birth mother feels guilty about rejecting him when he came to her, asking to be a part of her life, and feels responsible for the man he became. The team convinces her to testify against him when they point out how he has been tying her in to each murder he commits.

Source: SpoilerFix