Ok, Here is what I think. There are 2 ppl involved here. 1 is the doctor that went missing 8 years ago, and the other one is the PDM chairman.
What we need from the first victim is the water he heard, and these 2 lines:
"being near the cabin, but no time to reach it".
The PDM chairman obviouslt wasnt watching the TWD re-run because it started on 12PM (the conversation between dorctors confirms this).
Brandon doesnt even have a clue whats happening, even if he is the killer, we have no evidence whatsoever, so im crossing him out.
The "encrypted" message that they found, basically, mdlck.r refers to the doctor who disappeared 8 years ago, and the rest are organs.
Let's get back to those 2 lines (well, there is only 1). Probably the cabin was the place where the surgery would take place. PDM chairman knocked out the victim, and the doctor was going to perform the surgery, since he didnt have much strength to do all himself. From that line, I can guess that something didnt go as planned, so, unlike the woman, they let the first victim escape on purpose.
I think that PDM chairman and the Doctor are the killers.
EDIT:
-Brandon Maley. You were one of the people throwing rocks at a local store. Who do you think you are? Do you know you could've hurt someone? Or the costs of what you and your fellas broke?
-Like I give a crap.. they were screaming at us from making noise and trouble on the streets. Fucking jokes.
-Ah, you're with the "P.D.N.", saving lives, donating organs, huh? Said the officer in a sarcastic way.
-Yeah. Got a problem with that, cop?
-Where have you guys been the last 2 years? I though the motion was done.
-Almost, but since someone has been killing and stealing organs, we're back on track. Because that's what some people need, a lesson.
-You scumbag. Who gives you the right to say who gets to live or die?
-Who gives them the right to let people die in hospitals cause they don't have 0 negative blood to receive? Huh?
-So that's the right way? Kill people, save others? People are still dying though.
-Not all. The liver guy survived, didn't he? So still, we mostly win.
-Well, here's your victory. Have fun sleeping in the interrogation room. Plus, you're now a suspect for the murders as well.
-What? Are you serious? I didn't kill nobody.
-Well, you did say some things that can be used against you to consider you an accomplice, it's all recorded.
-This is a fucking joke. Now I really wish I was the one I killed them! I wish the killer teaches you a lesson too you bastard!
It would be great if you told me who says what.