I do believe that somehow, we're going to see Brett return in the future.  However, while I think that Brett is involved, I'm not ready to say that he's Redjohn.

What I want to bring up is that, according to e5, the person who attacked Tinsley has a tattoo on their left arm.  As someone here observed, in e1 of Season 1, there is a shot of a paramedics team member loading a body into an ambulance, and then there is a slow-motion close-up shot of their LEFT ARM with a tattoo of what looks like the Grim  Reaper.  This CAN'T just be coincidence.

How this all plays into the bigger story I'm not sure, but surely, I'm not alone in thinking that this has to be connected somehow, no?