Due to some internet difficulties I haven't seen the latest ER episodes but as this run comes to a close I see that my initial guess of Thomas as the RcK was wrong.  My next guess was another FBI agent.  Maybe it was a late night viewing but I thought I remembered York talking about an agent who had either previously come to Greenvale or was due to arrive.  Briefly I believed Michael was the culprit because of his finger shaking but file that under coincidence.  Looks like the ERunners were right after all.  Anyways looking forward to these last episodes.  When both teams wrap it up I cringe thinking about everyone's 2 cents concerning the next Run accompanied with some form of "I'm calling it...".