Born in the Bronx, Conlon spent most of his childhood in nearby Yonkers. He attended Regis High School and graduated from Harvard in 1987 before joining the force in 1995. Conlon's police experience focused on patrolling city-owned public housing developments, as well as arresting street-level drug dealers after observing their sales from surveillance posts. In 2002, he was promoted to the rank of detective, and was assigned to the Bronx's 44th Precinct. He retired as a Detective, Second Grade, in 2011 after 16 years with the department.
After college Conlon wrote a novel which remains unsubmitted and unpublished. His first published article for The New Yorker was "To the Potter's Field" (1993), a bleak piece about Hart Island, New York. After joining the NYPD, Conlon wrote the Cop's Diary column for The New Yorker from 1997 to 2000 under the pen name Marcus Laffey. In the Sept 12. 2011 issue of the New Yorker, Conlon wrote a piece in the Talk of the Town section titled "Paying Attention" about 9/11 and his final days with the NYPD detective unit. He plans to continue writing.
The column resulted in a nearly $1 million advance for Blue Blood (2004), which covers Conlon's years in the NYPD, his work conducting street-level narcotics enforcement in the Housing Bureau, his family's law enforcement background, and various anecdotes about the history of policing. The book received a favorable review on the cover of The New York Times Book Review, debuted at #9 on the Times Best Seller list, and remained on the list for two weeks. Conlon appeared as a guest on National Public Radio's talk show Fresh Air. The book was the basis of a 2007 television pilot that NBC commissioned but ultimately did not order.
Red on Red
Conlon turned to fiction with this novel of police life that strays from actual NYPD investigative practice. Nick Meehan, a New York City detective slipping into mid-career burnout, is assigned a special case for Internal Affairs to investigate a suspected dirty cop. Meehan and his new detective partner, Esposito, look into a variety of other cases, including the apparent suicide of a recently arrived Mexican immigrant woman, gangland slayings by rival drug dealers (called "red on red" or criminal on criminal killings), and a serial rapist. In between writing about crime, Conlon's book examines the personal lives of his two main characters, the alliances and loyalties, the emotional tolls, the temptations, the shades of gray inherent to police work. The pace may be slower than the average thriller, but this novel was targeted to appeal to readers of literary crime writers such as George Pelecanos, Dennis Lehane, and Richard Price.
- Blue Blood (New York: Riverhead, 2004) ISBN 1-59448-073-7
- Red on Red (New York: Spiegel & Grau, 2011) ISBN 978-0-385-51917-5
- Porter Brown, Nell. "NYPD Crimson". Harvard Magazine, January–February 2005.
- Goldstein, Joseph; Baker, Al (21 July 2011). "A Writing Detective Retires to Focus on Books". The New York Times.
- 'BLOOD' MONEY The New York Post, 23 November 2007.