I was just rewatching the seaon 4 finale - Crimson hat and i figured it out Renembeer when Darcy is on the phone to 'BILL' wile she is mesuring the dead body well heres what I think wDarcy has to be an acomplice of RJ res why because it was her that couldnt or didnt want to beleive that PJ had killed Rigsby and Lisbon so she tried looking for clues to tell RJ she messurs the body and she knwos it is not Rigsby so calls her friend Bill who is Bill you ask well Bill is a nickname for William as in CBI FBI OR Homeland security they go by there last names ll that could mean that this bill charictor is RJ witch would mean RJ's last name is William/s and also he has to be in law enfocement as Darcy told him that she wants arrest warrents for all the memebrs of Lisbons team. Darcy is the friend in the FBI that RJ was talking about in the limo and who do we know that fits Red Johns description is always in the background was the last one to be seen with Wainwirght and that we do not know his last name CBI RON!!! WHAT DO YOU GUYS THINK