THE O.J. SIMPSON MURDER TRIAL : Author Leaves Trial, Joins Search for Son

Best-selling author Dominick Dunne has broken off his reporting on the O.J. Simpson trial to join the search for one his sons, missing since last week in a rugged area along the Arizona-Mexico border.

Alex Dunne, 38, of San Francisco was last seen late Friday evening, leaving his ailing mother’s Nogales, Ariz., home in her car, a beige 1980 Toyota Corolla station wagon, his father said Tuesday. In the back of the car, Dominick Dunne said, was a mountain bike.

“He’s an outdoors guy who knows about hiking, biking, trails . . . he really enjoys all that,” Dominick Dunne said. The 69-year-old writer--who has been covering the Simpson case for Vanity Fair magazine and CBS television--flew to Nogales on Monday, the day after Alex Dunne was reported missing.

“There’s always reason to fear,” Dominick Dunne said Tuesday. “It could be sunstroke, snakebite, anything. Or worse.”

Nogales Police Lt. Frank Carrizoza said Tuesday that foul play was not suspected.

The station wagon sports the distinctive Arizona license plates carried by handicapped drivers, and police hope that finding the car will lead them to Alex Dunne, Santa Cruz County Sheriff Tony Estrada said. The search focused Tuesday on the mountainous Coronado National Forest near Patagonia, Ariz., about 20 miles northeast of Nogales, Estrada said.

Two helicopters--one manned by U.S. Border Patrol agents, the other by a crew from the Arizona National Guard and the U.S. Forest Service--joined Tuesday in the search, said Larry Tiffin, manager of the Nogales International Airport.

Alex Dunne’s older brother, actor and director Griffin Dunne, 40, also helped search, Tiffin said.

His younger sister, Dominique Dunne--an actress best known for her role in “Poltergeist”--was strangled to death in 1982 by boyfriend John Sweeney. He was convicted of manslaughter.