Unless the sheriff somehow has the magical ability to falsify every piece of evidence somehow, there is no way his story will hold up. Just for the simplest thing, the bullet in Shelby didn't come from his gun.
Unfortunately, if the sheriff has those magical powers, being dirty is not a problem. He can avenge himself for old buddy Keith's death and Shelby's too. He wouldn't even have to frame Norma and Dylan, and his magic powers would keep him from suffering from blowback.Also, if the sheriff was dirty, then Shelby had no reason to keep any of his activities, including stealing the evidence against Norma.
The simplest explanation is that the rest of the world doesn't really exist in this fictional universe, so no one will ever ask the sheriff to produce any evidence. This is not really a good way to intensify the drama.
The questions about whether any scene is real is tending to undermine the impact. It's distracting.
Monday night was amazing in a completely negative way. The Bones finale was fatuous, Defiance went in for magic and Bates Motel had this mess.