I have never said I've known anything. I've only ever said I have made deductions.

I believe the obvious choice was Shinjiro, possibly Mitsuru. Please note that this depends solely on the deduction that Theodore is Mafia being correct. On the proviso that it is, everything else falls into place. This does not happen from any other starting point. While I cannot guarantee the accuracy of my logic, I'm certainly confident enough in it to risk my life on it. I simply do not believe in coincidence.