Thomas Reppetto, a former Chicago police officer who became a respected historian of policing and the leader of a nonpartisan watchdog group that researches ways to reduce crime in New York City, died on Tuesday at his home in Mount Vernon, N.Y. He was 88.

His wife, Christa Carnegie, said the cause was congestive heart failure.

Dr. Reppetto brought a street cop’s experience and a scholarly perspective to the Citizens Crime Commission of New York City, a small, business-funded organization, which he joined as president at its inception in 1979. He became a prominent advocate for solutions to criminal justice problems like shorthanded, overwhelmed police forces and the sale of illegal firearms.

And he was a reliable expert to call on when the news media needed a Harvard-educated former officer to discuss crime and policing.

“Tom was an extraordinarily strong advocate for the importance of policing — but appropriate policing,” William J. Bratton, a former New York City police commissioner, said in a phone interview. “He loved being a cop, he loved being the head of the commission, and he was cleareyed about the excitement as well as the flaws of the profession.”