How Do You Know Mr. Blue?

You are a private investigator. You have been hired by the enigmatic mega-corporation C-Corp to track down the whereabouts of a "Mr. Blue", an employee of theirs who has gone missing. The instructions were simple but clear: find him by any means necessary. Your first assignment is to interview Mr. Blue's immediate co-workers about his disappearance. They're all claiming ignorance, but someone is lying. Find out who. Best of luck, detective.