Like some sort of gruesome trail, you may find several corpses of a certain BLU asshole strewn about. Trying to poke one may result in it dissolving, since some of these are decoys being left behind both to obfuscate his actual deaths and to minimize the damage his body is taking; the real corpses have their masks super-glued on, so it can't be removed without destroying the face.
If you keep track of inventory, you may notice that supplies of painkillers--morphine in particular--has been coming up short in the last few days. Of course, given the current situation in town, you may not be able to nail down the perp, but maybe you might be able to catch him in the act?
C: 504 Ricardo Street, BLU Medic's house
It starts with one polite bell ring, followed by a few more less polite bell rings, followed by an increasingly impatient pounding on the door. If nobody answers after that, the house is going to get broken into by somebody who looks like a bizarre cross between a mummy and the Invisible Man.)