I'm assuming given the trailer for 6:02 that the list may be a decoy, and that the 6 remaining suspects may just be disciples. Going through the other suspects listed on this site, one name jumped out at me. Royston Daniel. Hasn't been seen since season 1, but neither has McAllister, and Smith made only 1 appearance in season 5. So quantity of times seen is obviously meaningless.

We know that RJ has disciples, who better to control people than a professional hypnotist? 

He is well presented, well dressed, very intelligent, could easily have put himself in peril to throw Jane off the scent, plus i believe they shook hands too. Lorelai said she was surprised that PJ and RJ didn't become friends, i could see PJ and Dr. Daniel being friends, they both have similar traits.

He fits Rosalind's physical description too, the only thing that puts me off him is that he's called Royston, can be shortened to Roy, and that would be just too obvious, unless he's hiding in plain sight?