I live in the area and have watched the 'show' on Netflix.
Totally slanted toward the defense. Avery and his nephew are guilty as hell. The nephew confessed to how many people? He didn't make those details up, not smart enough.
We drove by the Avery salvage yard once - pure evil coming from that place. Wouldn't let my husband stop the car.
Regarding the nephew, from what I've seen in the first four episodes, he was fed those details by the detectives. In one interview, the detective pleads with him several times to tell them what they did to her head. After struggling a bit, the kid says the he cut her hair. Not the answer they wanted, so they press again. "What did you do to her head?!", the detective asks, exasperated. The kid says,slowly, " We punched her."Finally, the detective exclaims, "Who shot her in the head?" That's how the kid knew the details. They were forced into him, time and time again.
As for Avery, I think so far, it's less clear. I do believe that evidence could be planted, but I can't imagine any other way the girl's body ended up in the fire pit, except by Avery. The whole thing is fishy, to be sure. The overall lack of evidence, except for the body is puzzling. As for Brendan's conversion, I regard that as pure fiction, coerced by lawyers on both sides. His first lawyer, Len Kachinsky, comes off as a total slimeball.