--------------------------------******* SPOILERS BELOW*******-----------------------------------------
This occurs during the DLC where you have to catch Jean Archer and question her.
Watch Cmdr. Fleischer tells you that a patrolman spotted her at the Western Union Office on 253 South Hill, less than a minute away down the street if he ran, so you now have to run to catch her.
WARNING: If you do not quickly run after her, you will miss her, and will not be able to get three questions and find one clue needed to complete the case. If you miss her, restart from your last checkpoint.As you get to the Western Union Office, you confront Archer, where she is trying to quickly get money cashed, but you stop her just in time. She tries to seduce Phelps to avoid questioning, but unfortunately, Phelps is a married, faithful man

, and begins questioning Archer.
Jean Archer:Stolen Kaiser Frazer: Doubt
Association with Belasco: Lie
Evidence: Belasco's ownership papers
Stolen auto courier: Doubt
If you asked all the questions and correctly branched them during questioning, you should get the achievement.
----------------------------------------------------------------
Those who wish to vote negative, at least please give the courtesy of explaining why you voted it down. I simply explained my method of what worked for me to get the achievement.