A special prosecutor has absolute immunity for incidents of nondisclosure and conspiracy tied to the prosecution; such acts cannot be used to establish a conspiracy prior to the beginning of the prosecution.
Prosecutorial directives made by the judge did not strip him of absolute judicial immunity, as they were not binding on the prosecutor.
http://media.ca8.uscourts.gov/opndir/18/06/171667P.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.