I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director!
Deputy AG Rosenstein wrote a memo for the president that did not outright urge firing Comey but provided plenty of "for cause" cover in case he did that.
In the above tweet, Bozo is universally believed to be alluding to that memo and, as is his wont, lying about it.
And, anyway, it is not Rosenstein but Mueller, a man appointed for the job by Rosenstein to Republican and White House applause, who is investigating the whole Russia thing.
When the firing occurred, it was immediately recognized by everyone - and Bozo himself has since confirmed - that the real reason was that Comey would not play ball with Trump and drop any part of the Russia investigation, including the Flynn part.
It was then and is still generally understood that the Rosenstein memo was a mere pretext, whether or not, as was then and is still suspected, the White House or the president himself actually requested that Rosenstein provide the memo.
But in the same tweet The Greatest Blowhard Ever confirms he is indeed under investigation.
Could be he was just playing into the accepted narrative that he is, and actually he has not been notified by anyone that he is, and has no knowledge that he is.
All the same, that is not how his liars are now making the case he admitted nothing of the kind in the tweet.
Update, 06202017, 0849 hrs EDT.
His surrogates now explain his tweet was in response to a preceding WAPO report based on an anonymous source that he was under investigation.
So it isn't independent confirmation.
Neither Trump nor anyone in the White House has any source on this matter apart from the media, themselves.
The very scenario I speculated.
Update, 06212017, 1421 hrs, EDT.
Rosenstein unavoidably comes out of this rather smelly, I think.