Oscar-winning screenwriter-TV scribe-author William Kelley (“Witness”) died Monday of cancer in Bishop, Calif., where he had lived for several years. He was 73.A Staten Island native from a prominent political family, Kelley studied for the priesthood at Villanova, but decided against enter holy orders and instead moved on to become a Phi Beta Kappa scholar at Brown U., Harvard Grad School and Harvard Law School with a stopover in the Air Force between WWII and the Korean conflict. But he was no effete intellectual. He was an Air Force boxer and, by his own description, an “obstreperous,” hot-tempered man who enjoyed a good fight and never shed his reputation as a “bad boy.” He got his first TV writing credit in 1955, with an episode of “Marshall Dillon.” Two years later, he had found his way to the publishing biz as an editor at, successively, Doubleday, McGraw-Hill and Simon & Schuster, first in New York and then on the West Coast. In 1959, Doubleday published his novel “Gemini,” which became a bestseller. He also edited designer Norman Bel Geddes’ autobiography “Miracle in the Evening” (1960) for Doubleday. In the 1960s, he had two more novels published: “The God Hunters” and “The Tyree Legend,” both from Simon & Schuster. During those years he also began to work more in television, and by the end of his career he accumulated more than 150 TV credits. He wrote for copshows “Serpico” and “Petrocelli” and actioner “Kung Fu” but made his greatest mark in oaters, winning the Golden Spur award for his work on “Gunsmoke” (1970) and “How the West Was Won” (1975). During the last season of “Gunsmoke,” he had an idea for an episode that would have Marshall Dillon save an Amish girl from thugs, then fall in love with her. “Gunsmoke” never made the story, but it was eventually filmed as an episode of “How the West Was Won.” Years later, former “Gunsmoke” writer Earl Wallace, a former police reporter, approached Kelley about updating the story to contemporary times. They co-wrote the screenplay, which became known as “Witness.” The film, directed by Peter Weir and starring Harrison Ford, earned the pair a WGA award and the 1986 original screenplay Oscar, shared with Wallace’s wife Pamela. (Ironically, it was Kelley’s only produced screenplay. He never worked with Wallace again and never had another script produced.) Kelley spent his later years living in Bishop but was a familiar face at writers conferences and seminars, where he invested much time into working with young writers. He is survived by his wife, two daughter and three grandchildren.