Reppetto joined the Chicago Police department in 1952 and became the commander of detectives. While working there, he pursued his PhD, but once it was completed and he rejoined the force, but, however, he was sidelined from holding advanced positions. In 1970 he became a criminal justice researcher at the
Joint Center for Urban Studies of M.I.T. and Harvard. In 1971 he moved to be a professor at New York City's
John Jay College of Criminal Justice; he eventually served as dean and vice president of the school. In 1979, Reppetto was approached by a group of businessmen who formed the nonpartisan New York City's
Citizens Crime Commission. He served as the president of the commission for over 20 years. He advised New York City mayors on how to reduce crime, pointing to many historical mistakes which led to public distrust and unrest of police officers. == Publications ==