DeMille returned to the States and went back to Hofstra University where he received his degree in Political Science and History. He has three children, Lauren, Alexander, and James, and still lives on Long Island.
DeMille's earlier books were NYPD detective novels. His first major novel was By the Rivers of Babylon, published in 1978 and still in print, as are all his succeeding novels. He is a member of The Authors Guild, the Mystery Writers of America, and American Mensa. He holds three honorary doctorates: Doctor of Humane Letters from Hofstra University, Doctor of Literature from Long Island University, and Doctor of Humane Letters from Dowling College.