SALEM – Rape and assault charges against a Lynn man were dropped after the victim in the case declined to testify at trial.Jerry Koch, 25, of 50 Andrew St., was scheduled to go on trial Tuesday morning in Salem Superior Court on three counts of rape and a single charge of assault and battery involving sexual misconduct with a Lynn woman in the summer of 2005.But Assistant District Attorney James P. Gubitose told Judge Howard J. Whitehead he was not proceeding with the trial and was dropping all the charges against Koch.Gubitose said that the commonwealth could no longer proceed with the case because the victim “no longer wishes to testify” and the commonwealth cannot proceed without her full cooperation.Koch, who was indicted by a grand jury in August 2005, has been free on $2,500 cash bail since being arraigned in Superior Court.