Wow, I can't believe someone dug up my old thread. I appreciate all of the feedback and ultimately decided to tell the professor exactly what I saw without mentioning the student by name. I guess my hope was the professor would look out for the type of behavior on the next exam.
First of all, the professor was very grateful that I came forward and indicated that he had several methods to catch cheaters. He said that his own methods led him to the same conclusion that I reached and he would deal with this accordingly. Needless to say, the individual in question never showed up for another class after that day so the professor was obviously more clued in than I thought.