The scenario you described, where new evidence is found but the prosecutor does not pursue a new trial, can be seen as a violation of the defendant's constitutional rights, specifically their rights under the:
Amendment: Sixth Amendment
The Sixth Amendment to the United States Constitution guarantees the right to a fair trial, including the right to due process and the right to confront witnesses. If new evidence that could potentially exonerate a defendant is discovered, the failure to pursue a new trial may be viewed as a violation of these rights.