John Henry Carpenter became a suspect in the slaying of actor Bob Crane almost immediately, when he called the Scottsdale, Ariz., apartment where Crane's body had just been found and caught police Lt. Ron Dean's attention by failing to ask if anything was wrong, authorities said Tuesday.

"He returned to the scene of the crime--by phone," said Dean, now retired. The lieutenant spent a decade investigating a case that became one of the entertainment industry's longest-running, most provocative murder mysteries.

This week, Carpenter was arrested for the June 29, 1978, murder of the wisecracking star of "Hogan's Heroes." Though it took 14 years for prosecutors to charge the 63-year-old Torrance resident, Dean and other authorities said the case has always centered on the squat electronics company employee and his puzzling friendship with the Hollywood actor.

Sex and videotape are what linked the two men, according to Dean, his collaborator on a book, Robert Graysmith, and other sources.

Before video cameras became a common household item, Crane enjoyed recording his numerous sexual encounters with women, and Carpenter became an informal technical assistant--selling him state-of-art equipment, helping him set it up, sometimes appearing on camera, investigators said.

When Crane traveled to appear in local theaters--his reason for being in Scottsdale--Carpenter would follow, basking in Crane's celebrity and his ability to pick up women, Dean and Graysmith said. Many remembered Carpenter for his jet-black hair.

"Everybody said he was pretty much a hanger-on," said Graysmith, who has written a book on the case with Dean. Crane introduced Carpenter "variously as his manager, videotape maintenance man--things like that," Graysmith said.

Over the years, rumors about Carpenter's connection to the case have followed him from the nightspots of Scottsdale--where he had been seen socializing and arguing with Crane days before the actor's death--to the tidy, blue-collar Torrance neighborhood where he lives with his wife, Diana.

Carpenter has worked for the last 4 1/2 years at Kenwood USA, a Carson electronics company where he is national service manager. Before that, he worked at the Sony and Akai electronics companies.

"Everyone around here talked about the rumors--behind his back, of course," said Donna Waag, a neighbor of Carpenter on Doty Avenue. She described Carpenter as friendly.