Jose

 

Jose is Ricky's former best friend.  He was also Laura's friend at one point.  But after a botched brainwashing (discovered later in the book), when he sees new recruits going through some sort of initiation, he becomes angry, manipulative, and fixates on Laura being a witch.  The "bad guys" let him believe that he saw a witch's ritual, and that Laura was one of the ones he saw since it works to their advantage.  He later kills Ricky's father in an attempt to kill Laura.  He is going through intense deprogramming to undo the botched brainwashing and to get any information about the other agency to help Laura and the others find the rest of the missing children.