WHEN A BELOVED COLLEGE PROFESSOR VANISHES, WHAT DO HER HUSBAND AND HER LOVER KNOW? -- "48 HOURS MYSTERY," SATURDAY, APRIL 29

When Louisiana Tech University professor Stephanie Pepper Sims vanished in early January 2003, what did her husband David and her lover, Wayne Guidry, Jr., know about her disappearance? Correspondent Peter Van Sant reports for 48 HOURS MYSTERY: "Deadly Proposal," to be broadcast Saturday, April 29 (10:00-11:00 PM, ET/PT) on the CBS Television Network.

Stephanie grew up in Jonesboro, La., a small town where she excelled in school and then became a well-liked English professor. In February 1999, after just six months of dating, Stephanie married David Sims, a successful accountant, 10 years her senior.

But, two years into their marriage, David says he and Stephanie were growing apart and were sleeping in separate beds. David admits to being controlling and had always insisted the couple have separate bank accounts. Stephanie had told her husband she felt "lonely."

In November 2002, Stephanie and her friend, Ginger Steward, visited a local bar where Stephanie met Wayne Guidry, Jr. He told the women he was a professional golfer and was spending some time in the area hunting during the off season. Ginger said Guidry swept Stephanie off her feet. Less than a week after Stephanie met Guidry, she told David she wanted to separate � though she didn't mention that Guidry was the reason. David agreed to the separation and hoped it could save their marriage. He even helped Stephanie move into an apartment.

Stephanie remained in occasional contact with David, but she was having trouble keeping her affair private. David says there were clues that Stephanie may have been seeing someone. He says she once received a call while they were together and she claimed it was her female friend, but David recognized it was a male's voice. David also found a man's golf hat in the trunk of Stephanie's car, though she claimed it was her father's.

Five weeks after the affair began, Stephanie disappeared. Stephanie's mother feared the worst when her daughter's daily calls to her abruptly stopped. David told police he had nothing to do with his wife's disappearance and passed a lie detector test. Wayne Guidry, Jr. is the last person to have seen Stephanie. But, without a body, police had a tough time making a case against Guidry. He, too, maintains his innocence. What happened to Stephanie Sims?

48 HOURS MYSTERY: "Deadly Proposal" is produced Peter Henderson and Mead Stone. The senior producer is Anthony Batson and the executive producer is Susan Zirinsky.