After graduating from Sacred Heart, John L. Duffy attended Manhattan Prep on a partial IRT Holy Name scholarship, where he was an honor student, class officer and varsity member of the track and basketball teams. He graduated in 1956, and joined the FBI as a clerical employee in 1958. He worked the night shifts while attending CCNY, graduating in 1964. He was appointed a Special Agent of the FBI. After training school in Quantico, VA, and Washington, DC, he was transferred to Indianapolis, IN. Subsequent assignments took him to Gary, IN, Kenosha, WI, Washington, DC, Baltimore, MD, Washington, DC, and, lastly Buffalo, NY. During his agent career, he served in many assignments including Supervisor, Personnel Officer, Inspector and Special Agent in Charge from which he retired in October 1988.
After his retirement, Duffy served as the Director of Investigative Services for the General Counsel of Ernst & Young LLC for almost 15 years, retiring in 2003. He then served as a consultant for the United States Conference of Catholic Bishops until last year.
Duffy met his wife, Betty (nee Cavanagh) in Rockaway Beach in 1956 at the Vinegar Hill Tavern, and they were married in 1960. They have two children: Jean Marie and John, and four grandchildren. The Duffys live in Orchard Park, NY, and spend the winter months in Florida.