When you engage in conversation (or other such interaction) with an alleged perpetrator of a crime, make a Knack Skill roll. On a success, if the target is guilty, he will leak a piece of information that connects him to his crime. Before expending effort on using this Knack, let the Storyguide know, and she should tell you if the target does not have any valuable information to leak — which in itself can be helpful in an investigation.