We often hear politicians-- and U.S. presidents especially-- being criticized for weighing in on criminal cases on the grounds that their comments could prejudice a jury. Most recently Joe Biden and Rep. Maxine Waters were criticized for premature comments calling for a guilty verdict in the Derek Chauvin trial. The Chauvin defense raised Waters' comments in particular as an objection, and although it was unsuccessful, the judge suggested it could be raised on appeal. Another classic example would be the defense team for Charles Manson pushing for a mistrial because Nixon declared him guilty.
My question is: has there ever been a case of a politician's improper statements actually leading to a major setback for the prosecution? What I'm looking for is not examples like the Manson or Chauvin trial where the extent of the setback was unsuccessful defense motions that caused the prosecution a bit of a headache. I'm looking more for examples where the the comments led to some sort of tangible win for the defense, be it a mistrial, dropped charges, reduced sentence, thrown out evidence... etc.