I bet it is one of the twelve, or the murderer :P

umm some guy thats good

a goodie- the guy that took the picture of the twelve- that's my theory, there were 13 people in the room (one taking the pic!) and he's not the killer but knows who is!

I could see Adam Monroe being a photographer, that may explain the painting of the vial, something to do with a photographer's Dark Room perhaps?

I think it was the cell partner of peter while he was a prisoner at the Company HQ.. In one of the pictures from the series of 8 you can see peter with some guy (Adam?) And a Bio-Hazard symbol (maybe the company kept him there cause he was dangerous, with the blast and all..)

HELLO?! From the minute, Episode 6 ended I was thinking Adam Monroe must be the Killer - Maybe, possibly Kensei.

Check the heroes images. I uploaded one and named it "Adam Monroe hein¿", you can see in it a screen from the heroes mobile game, and it confirms that adam was amond the company founders

adam is kensei , he just changed his name .
he is peter's cellmate and the killer of kaito