Get this in Chapter 7, when you enter the apartments south of the train on Adrianna Street, a couple mentions an injured man. Head south a couple of screens, and then west and talk to Derrin. You'll need to give him a Painkiller before he'll mention J. Langley. Later, at the end of Chapter 9, J. Langley (Brent's boss) comes by to thank you for helping the police. At this point, you get a dialog option to ask for his full name, and then you can choose to have Brent investigate him.