Lennie was born January 2, 1940. He grew up in the Meatpacking District of Manhattan. A veteran of two failed marriages, Briscoe has two daughters, the elder Julia and the younger Cathy, and a nephew, Det. Ken Briscoe. Briscoe was an alcoholic, although in recovery.
After leaving the Army, Briscoe joined the NYPD in the 29th Precinct in Manhattan and walked a beat there with stops at the 31st and 33rd Precincts, also in Manhattan, and the 110th and 116th Precincts in Queens. Briscoe is regarded as perhaps the best homicide detective in New York. He is partners with Detective Reynaldo Curtis, and is Godfather to
Captain Elissa Mazza of the Unsolved Crimes unit (UCU).