The Departed (2006 movie): After Billy found out Sullivan's true identity, he entrused Dr. Madolyn with an envelope, but she never opened it. He later sent another package containing Costello and Sullivan's conversation to her. What could have been in the envelope he gave her earlier?
In The Departed, does Dignam kill Colin because he knows (and how he knows) he was the spy for Costello or just because he could not stand him?