When going for
In the room outside the police station where you find all the evidence there is a safe, in the safe (Level 3 Safe) is a bracelet. Take the bracelet.
Then when you go in to hand in the quest, the mother will ask if you found anything else. Just tell her no and the achievement will unlock.
The code for the safe is 7-1-9-6. Thanks to Riled Assassin for the code.