This is my "killer speculation" post. My proper reaction post will be posted directly after this.
And here it is.
After this episode I am a mix of "more confused than ever" and "okay maybe I might be getting close to my pick for most-likely-to-be-the-killer." I just can't tie all the threads together.
Going by this episode alone, my gut says that Joe Mills is a patsy. He's been framed. I mean, he's a creepy pedophile, but he's not the killer.
So if I'm following that thread, then who did the framing? Maybe the guy with the box of rings: Carl Reddick? I have suspected him more than once throughout, but if he's the one that planted the rings, then maybe it could work. The actor did have a huge bandage on his hand during the Holder/Reddick fight attack scene at the end, and it was pointed out that Bullet fought back hard during her attack, but it was flesh colored so it could be unimportant and production may have been trying to hide it as much as possible. They obviously weren't trying to make it stand out. The other thing is that Reddick took calls from Bullet, if Bullet spoke to him, not knowing who he was, and told him she knew who the killer was? He may have gone after her. That's why she doesn't fit the MO and that's why she specifically was targeted.
I just can't see Reddick being that... pro-active. This all seems like way too much energy for him. But there's a chance I could still be right and he's not acting alone.
But then there's Becker, and Henderson (unlikely), and Skinner (who I still have my suspicions about), and the P.O. and Joe Mills who wasn't in town for Trisha's death but still could be involved with the others, and Goldie (are we still counting him?) and possibly Dale (somehow) and it's all so confusing. I can't remember if any of those suspects have been ruled out completely as suspects. Skinner did show up just before Reddick came out with the box of rings. Maybe he's the one who planted it? I JUST DON'T KNOW!