Author William Murray, a writer whose series of popular mysteries featuring "Shifty" Lou Anderson blended racetrack characters, magic, and intrigue, died early Wednesday morning at St. Luke's Hospital in New York City from an apparent heart attack. He was 78, according to the Associated Press.Murray was in New York reviewing final proofs on two books, including "Dead Heat," his 10th "Shifty" Lou Anderson novel and first in nearly 10 years. Eclipse Press, the book division of Blood-Horse Publications, will publish "Dead Heat" later this year. He also recently completed a book on opera, which, along with racing, was one of Murray's great interests.Murray was taken to St. Luke's Tuesday after complaining of discomfort. According to Del Mar racetrack publicist Mac McBride, Murray suffered a massive heart attack at approximately 6 a.m. Wednesday morning.Murray, a native New Yorker whose mother was an Italian publishing executive and broadcaster, got a job as an editor with The New Yorker magazine in 1956. "I was a glorified reader," he once said, "reading between 60 and 80 short stories a day. But writing is what I really wanted to do, so I passed over to the writing side in 1961."Murray wrote the "Letters from Italy" series for The New Yorker over 30 years. In 1966, he moved to Del Mar, Calif., where he kept his primary residence until the time of his death. "I had decided I discovered paradise," Murray said about the seaside city that hosts a summer race meeting from July-September. Since then, whenever he was in town, Murray was a fixture at Del Mar, both during the live meeting and for simulcasting."Del Mar undoubtedly was his favorite racetrack and favorite place to be," said Joe Harper, the track's general manager. "His great wit and passion for the game made him a guy you wanted to be a friend with, and you were always entertained when he was around. We had a great relationship--professionally and personally. Racing is going to miss him, and I know I will, too."Murray's racing mysteries were filled with the rich characters and unique language of the racing world, a mystery in itself to many outsiders. "Tip on a Dead Crab" was so full of racetrack jargon, Murray once said, that "my mother had a terrible time reading it. She was my biggest fan, but she was never able to get through it. So in the second book, I tried to cut that racetrack terminology down so that outsiders could understand it. I tried to explain the terminology whenever possible."Murray wrote five plays and at least 10 others books, including "The Sweet Ride," which was made into a feature film, and "Malibu," which led to a television miniseries. One of his latest works, in 2000, was a novel based on his life: "Janet, My Mother, and Me: A Memoir of Growing Up."Murray is survived by his wife, Alice, and three children from a previous marriage: William Jr., Natalia, and Julia.