John Preston (dog handler)

John Melvin Preston (July 8, 1945 – June 2, 2008) was an American con artist, dog handler, and state trooper from Pennsylvania who testified for the prosecution in criminal cases across the U.S. in the early 1980s. Preston falsely claimed that his dog (named Harass II or Harrass 2) could perform feats of forensic detection far beyond the abilities of other investigative dogs.