Most prevalent information is Sessions recused himself bc Darryl Issa and his small cabal began to pull back support after 100ish democratic "turds" called for Sessions resignation. And Issa and cabal strongly suggested it, in some part to protect the Republican party, which was beginning to fracture even then, Ryan was not on board.
Recusal kept Sessions in place where he could see enough to keep T apprised and keep things as trumpish as possible.
It has been suggested T thought, arrogantly, he could twist things and the R party as time went on, underestimating the swamp and what did come out in the investigation.
When Sessions didnt/couldnt provide the T solution, T turned on him like he did on anybody else who failed to throw themselves on their sword for him. T thought he could bully his way through as he had in his previous life, and that has gone nowhere in the swamp.
Not a whole answer, but general thought from several in the area.
Comey was dirty. That was coming out. The appointment of Mueller wasnt "just" about the firing, it was about a snipe hunt for anything, the swamp being the swamp, get rid of anybody that can hurt the swamp.
@vh20 Gonna be an interesting book written one day about this shit...
There is information out there that Issa's committee ran over 24k investigations into the BO administration. Some of the same junk they investigated then blipped in Mueller and was also recommended by Sessions to be investigated b4 he departed, and no action has ever been taken on any of it. Swamp water is filthy water.
And not that it matters to the average reader, Sessions ran a Fudd by the book, manner of business. Probably 99% of everything he did would stand up under very strong legal scrutiny. He resisted a number of T's orders to do some things that were blatantly going to get everybody in trouble, look at who blindly did Trimpism and got indicted and who got roasted and fired, but never a threat of investigation much less indictment.
Another minor thing, in all the evidence seized, there is a bunch of criminal stuff, that will never see the light of day, small thing, statue of limitations... the swamp water is filthy...