Donald Trump just claimed that "I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director!"
This is an odd tweet for several reasons.
1. The man investigating Trump is Special Counsel Robert Mueller, an administration outsider who surely did not tell Trump to fire Comey.
2. The people who conspicuously told him to fire Comey—Attorney General Jeff Sessions, Assistant Attorney General Rod Rosenstein—aren't personally investigating him. Indeed, Sessions is fresh from stonewalling a Senate hearing to cover for his boss.
3. Trump admitted on national television he was planning to fire FBI Director Jim Comey anyway, because of the agency's investigation into the Trump campaign's Russian ties.
The best guess seems to be that Rosenstein has somehow angered Trump and is being instantly and publicly thrown under the bus in a way that will only serve to expose whatever new scrutiny Trump feels placed under by him.
But here's another hypothesis: Trump is just constantly bullshitting. It never stops. It means nothing beyond the passing moment of anxiety it subdues or the vindication it generates. It's the pathological face-saving blabbering of a man whose reality is constantly reconfigured to his own transient satisfaction.