Did you watch all of both seasons? You probably need to watch them again.
They don't necessarily have to come across the murder themselves. Far from it, they only need a few key people playing the game, which is shown.
First, you've got to remember that the state police have an axe to grind with Avery, even some of the same officers.
Secondly, they acted atrociously in this case, covering evidence, moving evidence, amending evidence. It's all there in the "show". And things like threatening the Coroner to the point she resigns, is just amazing.
Thirdly, combine the two and it's possible they only needed to think or want it to be Stephen and started the frame work in the form of tampering and concealment of evidence. It's partially all set up for them anyway. It's not a few days, it's more like weeks. Remember they re-search days later in places before finally finding critical "evidence". Things like the key - definitely very suspicious potential framing but the bullets are everywhere anyway, just got to find some DNA.
The thing season 2 covers well is the bones and the burning. Doesn't add up at all.
It's plausible that Bobby did it.
As a lot of people say on the show, the truth will come out eventually. But i fear it won't be any time soon.
Problems.
Regarding only a few people playing the game;
The level of conspiracy required to pull this off would require a large number of people operating at many different levels. Aside from the murder itself - the statements would also need to be falsified, things like the phone records would need to be falsified (
because the phone records implicate Avery and place him within close time and proximity of the murder) The witness testimony of people claiming their saw fires and things being burned, around the time of the murder, would all need to be falsified - basically if the whole thing is a conspiracy - everything needs to be falsified. It's almost impossible to pull off without being found out. (that's before we discuss how on earth Halbach's Rav4 made it's way onto Avery's property, along with the all the other evidence and her remains -
without anyone else noticing, something you haven't addressed, and to my mind not a single person has addressed this.
Regarding the motive that the police have;
The main motive the police had, would be to get out of paying the $36M lawsuit against them, which does give them a motive for framing Avery. However, there are too many inconsistencies in the framing theory;
- Halbach's death occurred somewhere on or around the Avery property, because this is where she was last seen alive.
- If the police wanted to frame Avery by murdering Halbach, they'd have to do it on his property or have someone else do it for them (because this is where she was last seen) - which would be very difficult to pull off, along with planting all the evidence without being found out.
- If an unknown assailant murdered Halbach and the police wanted to frame Avery for it, it doesn't add up that the victim was last seen alive near Avery's property having just received a phone call from him?
- It would make more sense, if she was last seen alive 50 miles away - but she wasn't, she was witnessed directly having contact with Avery on or around the day of her disappearance, which is very difficult to get away from.
Regarding the police acting atrociously;
This cuts two ways - it doesn't follow that an incompetent police force who are cutting corners, making mistakes out in the open - would be able to successfully pull off the above conspiracy theory, without it coming out somehow. The Manitowoc police force are not masterminds, they're mostly just regular cops. With the amount of attention this case has received from all manner of notable people - especially considering the immense financial and personal reward of uncovering such a thing - nobody has uncovered any evidence thus far, that points to any sort of conspiracy theory.
Regarding the timeline;
The timeline of the murder is less than 5 days, she's last seen alive on he 31st Oct, reported missing on the 3rd of Nov, her vehicle is found on the 5th. The searches I put down to shoddy police work, I don't see anything suspect about the key at all, it's more likely it fell out and was found on subsequent searches rather than being planted. Ask yourself this; if this was such a planned conspiracy theory - why not just make sure it's found on the first search? why go back two or three times just to drop a key on the floor? It doesn't stack up.
It's interesting, when you have a problem and two theories - quite often the simplest and most likely explanation, is thrown out and replaced with a gigantic pile of flim-flam, it's almost as though people can't deal with a simple likely explanation for something, even when it's backed up by evidence - people want to throw that out.