I'm not gonna lie -- I don't think I've read nearly as much as you seem to have on this case, aside from a few minutes of Googling last night. I'm in the camp that thinks there is reasonable doubt about his guilt (based on what was presented in the series), but I am no where near convinced he is innocent either. There are a couple reasons that I think this. (I'm gonna bullet point them out -- not to be annoying or condescending, I just couldn't write a clear narrative while watching the national championship game)
First, look at who's the defense and who's investigating:
1 - Steven Avery had two extremely intelligent, extremely well respected attorneys working his defense.
2 - Calumet and Manitowoc counties are small, rural counties. I doubt that there are many homicide cases that are investigated in them -- especially under circumstances when a department has forfeited its rights to investigate to a neighboring county.
3 - You combine expert criminal defense attorneys and small-town, likely inexperienced, sheriffs in a chaotic situation, and I'd fully expect the attorneys pick apart the procedures taken by the cops.
Second, how do you plant all of that evidence (assuming the sheriffs didn't kill Halbach to frame Avery):
1 - You'd first have to find the car. If Manitowoc is anything like the rural areas I know, it's probably filled with seldom used backroads, abandoned private roads, old logging trails, etc that would be a prime place to stash away a car.
2 - There are thousands of concerned citizens going about their every day lives, dozens of volunteers searching backroads, well-intentioned hunters traveling the remote roads all over the area with their buddies and sons, people out 4 wheeling, hikers and nature walkers, and maybe a few crooked cops who have their eyes out for this car.
3 - In order for that car to be planted in Avery's junkyard, you'd have to assume that one of few crooked sheriffs randomly stumbled upon the missing car instead of one of the tens of thousands of people going about their every day life. I think it's reasonable to assume that probably didn't happen, although the defense brilliantly brought in a random phone call where Lenk called to confirm the plate number (Honestly - if I was trying to frame someone for murder, I'd know what car I was looking for and not need call the Sheriff's office or dispatcher where all calls were recorded to confirm the plate numbers)
4 - Also, I don't believe the individuals who found the car were 'in on it' (though the ex-bf and brother creep me out). If I was trying to find a car in a junkyard, I'd probably start on the perimeter and work my way in the the same way that those volunteers did, so I don't think it was that weird the car was found quickly.
Next, you have to think about the body (I'm assuming the bones were Theresa's body -- I think they said there was still flesh on some -- but you may know better than me):
1 - There are two scenarios that I think would be most likely with the body if Avery was framed. A) Halbach's dead body was in her car or B) Halbach's body was hidden like her car was.
2 - If A) were true, I would have expected there to be significant evidence of Halbach's blood in the car, but I don't think that was the case.
3 - If B) were true, then one of the few crooked sheriffs would have also needed to find Halbach's body along with the car before anyone else in the county randomly stumbled across her. I think this is also highly unlikely.
Finally, I think you'd have to keep too many people quiet in order to frame Avery for murder:
1 - On day 1, you have a brother and an ex-boyfriend. You probably don't know who they are (I'd assume a prior relationship would have been exposed by the documentary). You'd have to have the audacity to go up to these two men and say "I know you are organizing a search for your sister and clues that would identify her killer, but instead, how about you do a few things that will help me frame someone I have a personal vendetta against, instead of trying to find the real killer".
2 - Then you'd have to find a volunteer that you tip off about where the car is and expect them to keep up a lie about a framed murder so you can fulfill a personal vendetta.
3 - Then you have to turn to a colleague and say 'hey, let's frame an innocent man for murder'.
4 - The deeper you think the conspiracy goes, the deeper you realize it's a stretch to have so many more people in on framing an innocent man.
Personally, this is how I believe things went down:
1 - The victim obviously arrived at the Avery compound.
2 - Halbach was murdered, but not in Avery's home the way the prosecution framed it
3 - The body was burned and the car was hidden in the salvage yard
4 - The car was found and soon after the body's remains were discovered
5 - Seeing the opportunity of the situation individuals with a personal vendetta against Avery decided to leave no doubt that Avery (out of everyone in the 'holler') committed the murderer
6 - Using the chaos and disorganization of an appointed investigator, one or two members of the sheriff's department continued to plant evidence by taking advantage of a poorly controlled small town/county law enforcement system.
7 - Dassey and Avery had terrible luck with their court appointed attorneys, especially Dassey who was just overmatched against a professional interrogator
8 - In even worse luck, a snake oil salesman DA was appointed to the case
9 - And to top it all off a media-influenced and personally biased jury was appointed
I think Avery was lucky enough to stumble on fantastic attorneys that showed the injustice of the system.
I do not believe that Sherriff Lenk was lucky enough to discover both the car and the body, before the thousands of others in the county did, to frame Avery.
I also do not believe that a body was burned on Steven Avery's property without his knowledge of it. Whether he, his nephew, his brother-in-law, or someone else killed her, I don't know. To me, it just seems like too much of a coincidence that a car and body were found by a crooked cop before anyone else and that they were able to influence so many other people to take place in their personal grudges.
And holy moly -- the second half is kicked off. I'd love to hear what people that know more about the case thinks about how I saw it -- I very well may be missing things due to enjoying some wine with the Mrs. while binging quite a few episodes on Thursday, Friday, and Saturday night...