it's definitely not Kirkland. he did shake PJ's hand but Lorelei had no knowledge of this because she was in prison at the time so it must be somebody from the past. Lorelei hadn't been in touch with RJ since she got into prison.

it's not haffner because he is too stupid to pull it off.

it's not brett stiles because despite differences PJ likes him and vice versa.

the most likely theories are actually most unlikely..that would be too easy

the idea of PJ's father seems plausible, however why would RJ go to such a great lenghts to make carnival surrounding at the place of killing Lorelei?

at the moment I still have no idea who RJ could be. I was thinking about JJ la roche as he has the ability to hold power over people (hence manipulating by Lorelei's words) but his physique is not that of RJ.

perhaps we get more clues at season 5 finale..