DeMille was born in Jamaica, Queens and resides in Garden City, New York, a village on Long Island. He attended Elmont Memorial High School in Elmont, New York, and spent three years at Hofstra University.

DeMille served in the United States Army as a First Lieutenant and saw action in Vietnam.

He is a member of Mensa.

Many of DeMille's books are written in the first person, and as such his books follow a linear plot line in which the reader moves along with the main character.

Although the tone of his writing varies with his books, he often includes a liberal dash of sarcasm.

Most DeMille novels, especially the more recent, avoid "Hollywood endings" and instead finish either inconclusively or with the hero successfully exposing the secret/solving the mystery while suffering in his career or personal life as a result. There are generally loose ends left for the reader to puzzle over, Night Fall being a perfect example.

DeMille often uses Long Island as a setting in his novels, for example in The Gold Coast, Plum Island, Word of Honor, and Night Fall. His most recent novels have followed two main characters, John Corey and Paul Brenner. At first, the story lines were completely separate, but there have been hints in the novels that they are part of a larger "DeMille Universe" that references events and characters in earlier novels, such as The Gold Coast and The Charm School.

DeMille has written himself into Up Country and Wild Fire. He takes about two years to write books because of extensive research, and because he writes them longhand on legal paper with a number one pencil.

Bibliography

• The Sniper (1974)
• The Hammer of God (1974)
• The Agent of Death (1975)
• The Smack Man (1975)
• The Cannibal (1975)
• The Night of the Phoenix (1975)
• Hitler's Children: The True Story of Nazi Human Stud Farms (1976) (as Kurt Ladner)
• Killer Sharks: The Real Story (1977) (as Brad Mathews)
• The Quest
• By the Rivers of Babylon (1978), ISBN 0-15-115278-0
• Mayday (1979, updated 1998) (with Thomas Block), ISBN 0-446-60476-3
• Cathedral (1981), ISBN 0-440-01140-X
• The Talbot Odyssey (1984), ISBN 0-385-29322-4
• Word of Honor (1985), ISBN 0-446-51280-X
• The Charm School (1988), ISBN 0-446-51305-9
• The Gold Coast (1990), ISBN 0-446-51504-3
• The General's Daughter (1992), ISBN 0-446-51306-7 (also a movie)
• Spencerville (1994), ISBN 0-446-51505-1
• Plum Island (1997), ISBN 0-446-51506-X
• "Revenge and Rebellion", in The Plot Thickens, ed. by Mary Higgins Clark (1997), ISBN 0-671-01557-5
• The Lion's Game (2000), ISBN 0-446-52065-9
• Up Country (2002), ISBN 0-446-51657-0
• Night Fall (2004), ISBN 0-446-57663-8
• Wild Fire (2006), ISBN 0-446-57967-X
• The Gate House (Sequel to The Gold Coast) (October 28, 2008), ISBN 0-446-53342-4
• The Lion (Sequel to The Lion's Game) (2010), ISBN 0-446-58083-X

Recurring characters

Detective Sgt. Joe Ryker, a tired no-nonsense plains-clothes-man whose natural understanding of his environment gives him an instinct for finding criminals. Famed for being a loner, he carries two weapons, standard police special .38 in an ankle holster and a shouldered .357 Magnum. Keller bears a resemblance in attitude and appearance to Harry Callahan. He appeared in The Smack Man, The Cannibals, and two other novels.

John Corey, a retired New York City police detective on special assignment for the F.B.I. He was introduced in Plum Island and reappears in The Lion's Game, Night Fall, Wild Fire, and The Lion.

Paul Brenner, an investigator for the United States Army's Criminal Investigation Division. He was introduced in The General's Daughter and reappears in Up Country.

Kate Mayfield, an F.B.I. agent. Introduced in The Lion's Game. She marries Corey and reappears in Night Fall, Wild Fire, and The Lion.

Colonel Petr Burov/Boris Though not explicitly stated, DeMille hints that Burov, the antagonist in The Charm School, is the same person as the mysterious "Boris," a character in The Lion's Game and The Lion.

Ted Nash, a CIA agent and arch-rival of Corey, who is introduced in Plum Island and reappears in The Lion's Game, Night Fall, and Wild Fire.

Col. Karl Hellman, Brenner's superior officer at the CID. Appeared in The General's Daughter and Up Country.

John Sutter, Susan Sutter, Felix Mancuso, and several other characters of The Gold Coast reappear in the sequel The Gate House.