What is a prosecutor's duty when they know that a witness has committed perjury?

"A prosecutor has a special duty commensurate with a prosecutor's unique power, to assure that defendants receive fair trials." United States v. LaPage, 231 F.3d 488, 492 (9th Cir. 2000) (addressing a prosecutor's duty when he knows that his witness commits perjury). "It is certainly within the bounds of fair advocacy for a prosecutor, like any lawyer, to ask the jury to draw inferences from the evidence that the prosecutor believes in good faith might be true." United States v. Blueford, 312 F.3d 962, 968 (9th Cir. 2002).