On Friday morning, President Donald Trump admitted in a tweet that he is, in fact, being investigated for obstruction of justice stemming from the circumstances of his firing of former FBI Director James Comey:
While Trump is saying that he “is being investigated for firing the FBI Director by the man who told me to fire the FBI Director,” that is not the case.
Yes, Special Counsel Robert Mueller was appointed by Deputy Attorney General Rod Rosenstein, who did write a letter suggesting Comey's firing, but the Special Counsel is there to take over for Rosenstein.
Attorney General Jeff Sessions had recused himself from anything related to the Russian collusion allegations, though he still endorsed Rosenstein's letter. The recusal made Rosenstein the effective Attorney General on those matters. Rosenstein can fire Mueller, but that doesn't make him the one investigating Trump.
Theoretically, Trump could be saying that Mueller told him to fire Comey, though that makes little sense since Mueller was not part of his administration.
The new tweet contrasts one from Thursday, when, stemming from the initial report of the obstruction investigation, Trump appeared to be denying that the report was true:
However, it could also be read to say that he had learned he was under investigation and was expressing frustration over that fact.
Like many Trump tweets, it can be read both ways.