I need to know the name of a movie... Details are below?

I saw a movie a while ago and can't remember much about it except the plot. There was a guy with seroius amnesia who was trying to find his wife's apparent killer. He starts leaving notes everywhere then eventually starts getting his notes tattooed on his body. In the end it turns out his secret informant was just using him to kill people and he wouldn't even remember the next day. If anyone knows what it's called i'd love to know...