Det. John J. Walker was appointed to the force on April 15, 1997. He was promoted to Detective on January 31, 2008, and retired out of the NYPD Tactical Training Unit on May 31, 2017. Because of illnesses he contracted as a result of his work on the rescue and recovery from the WTC attacks, he died on May 8, 2022. He was survived by his spouse and two children.