I just finished everything and I'm still not sure what to think. Michael is so unbelievably phony and dishonest, to me but between that and the blood are the only things I can see that are against him. To me, the motive was there, to an extent, with his outside relationships. He always portrayed his relationship as near-perfect even up until the final episode. It could not have been perfect if he was having an affair(s). I can only imagine what Kathleen thought about that and that could have certainly played a part in his motive. She finds out about this, and threatens to leave and he gets mad, or something similar. This is all still just speculation though but the motive could be there with that. Not to mention, there was a life insurance policy involved that the documentary never mentions.
For a documentary commissioned by Michael, I came out of it thinking it painted him as guilty, just by Michael's own actions and behaviors. He comes across like a narcissist and an egomaniac. However, the state really didn't have shit on him and Deever was a hack. The blowpoke theory was bullshit, Deever's tests were bullshit. IMO, there isn't enough evidence either way to rule out any doubt. My gut says he did it but I still don't know and my gut doesn't really know shit.