This may have already been mentioned, but I just finished the season and have not read the entire thread...there are multiple times where Detective Lenk's story was changed during the trial from his original statements made months earlier, so it would better fit with the prosecutor's timeline (e.g. the whole time log around the Rav 4 after discovery). Also, Coburn was still sniffing around evidence 4 months AFTER he was removed from the investigation for conflict of interest reasons.
How this does not scream reasonable doubt to the jury is beyond me, let alone, all of the other pieces of evidence that could be seen as reasonable doubt for Avery's case of innocence.
I have about a 25% gut feeling that he may have been guilty, as she was last saw on his property, but I also think evidence had to have been planted by the police to some degree. They search his trailer multiple times head to toe, and didn't find the key until like the 3rd day or something after already searching everything? Shady...