(written from a Production point of view)
Duff was born in New Orleans, Louisiana and has written plays and television screenplays for films such as the television drama Doing Time on maple Drive (1992, starring James B. Sikking and Bibi Besch), the television movie Without a Kiss Goodbye (1993, with Gwynyth Walsh and David Ogden Stiers), the drama Betrayed: A Story of Three Women (1995), as well as for several television series, including Popular, The Agency, J.J. Abrams' Felicity (2001), and The D.A. (2004), for which he also served as executive producer.
In addition he served as producer/ executive producer for the television movies Long Island Fever (1995, with Bill Smitrovich) and Texas Graces (1996), and Emilio Estevez' drama The War at Home (1996, with Geoffrey Blake). Duff received an Emmy Award nomination in 1992 for Outstanding Individual Achievement in Writing in a Miniseries or a Special for his screenplay for the television film Doing Time on Maple Drive.
Since 2005 he served as executive producer and writer on the Golden Globe winning drama series The Closer, which he also created. Star Trek performers Gina Ravera and Raymond Cruz are regulars on this show and James Avery, Jonathan Del Arco, and Bob Clendenin recurring guest stars. In 2007 he received an Edgar Allan Poe Award nomination with fellow writer Mike Berchem for Best Television Episode Teleplay for the episode Blue Blood, which featured James Black and Spike Silver. He also directed one episode, the third season episode Next of Kin: Part 2 in 2007.