There is such a thing as prosecutorial misconduct, but the remedy for that is civil (money damages to the defendant) and reversing of any conviction. The prosecutor walks.
IIRC, Nifong got in trouble because he knowingly elicited and advanced false testimony. IOW, he played investigator too.
I think there are ways to compensate for prosecutorial misconduct and Mueller appears to be guilty of it.
Vexatious, frivolous, or bad faith prosecution:
Hyde Amendment
1997
The Hyde Amendment is a federal statute allowing federal courts to award attorneys’ fees and court costs to criminal defendants “where the court finds that the position of the United States was ‘vexatious, frivolous, or in bad faith.’” In such cases, the federal court may allow victims to recover some of the costs they incurred in fighting the government’s investigation and prosecution by authorizing an award of attorneys’ fees and court costs to a criminal defendant when the prosecution’s evidence is so baseless as to be “frivolous.” Compensation awarded under this statute would come out of the budget of the specific federal agency involved, typically the United States Attorney’s Office.
Wrongful or malicious prosecution: