But an equally important part of his mandate is lesser known: his duty to write a report on his findings.
In this respect, Mueller, as a special counsel designated by the Justice Department, differs from other federal prosecutors.
Attorneys operate by a rule of put up or shut up—that is, they either bring criminal prosecutions or say nothing at all.
Some prosecutors will offer a brief explanation of their decisions not to prosecute, particularly in high-profile cases.
Rod Rosenstein, the Deputy Attorney General who was handling the Russia matter for the Attorney General, Jeff Sessions (who had recused himself), named Mueller under a specific federal regulation dealing with special counsels.
At the conclusion of the Special Counsel’s work, he or she shall provide the Attorney General with a confidential report explaining the prosecution or declination decisions reached by the Special Counsel.