A YOUNG MOM VANISHES AFTER VISITING HER EX-HUSBAND - COULD HIS ACCIDENTAL "BUTT DIAL" TO 9-1-1 HOLD CLUES TO WHAT HAPPENED?

"48 HOURS" Investigates in "Bad Boy"

When a young mom of a six-year-old daughter simply vanished, the focus turned to her ex-husband. He was the last person on record to see her alive. How she vanished remains a mystery today.

Michelle Miller and 48 HOURS investigate the disappearance of Shelley Mook and the hunt for clues to what happened to her in "Bad Boy" to be broadcast Oct. 29 (10:00 PM ET/PT) on the CBS Television Network. It's a case that exposes strained relationships and allegations of cheating, and it left the families wondering just what happened to their loved one who seemingly disappeared off the face of the planet.

Shelley Mook, a Tennessee school teacher, was last seen by her daughter entering the home of her ex-husband, Tyler Mook, on Feb. 28, 2011. The two had an on-again, off-again relationship, according to Shelley's friend, Brittany Brooks, who tells Miller there were "a lot of secrets" in Tyler Mook's house.

When police asked Tyler Mook where she went, he didn't say much. There were no clues. No crime scene. No body. A year later, though, the case took a twist when a 9-1-1 operator took an accidental call from Mook, who didn't realize his conversation was being recorded.

"Oh, they seen Shelley's car goin' down the road that night," he's heard saying on the call.

But if she went into his house, where did she go from there?

"No one knows what happened to her," says former police officer-turned- investigator Kevin Keele, who looked into the case for her family and now is a consultant for 48 HOURS. "But I'm pretty damn sure I know who did it."

Neither Mook - who used the fifth amendment more than 150 times to refuse to answer questions about what happened to his ex-wife in a family court custody case - nor his family or family lawyers would speak on his behalf to 48 HOURS. Local authorities also declined to discuss the case.

The search for what happened to Shelley Mook has gone cold. Tyler Mook, however, got himself into hot water in Florida when he was charged with attempted murder after attacking his then girlfriend on a boat trip.

Would that case reveal any clues to what happened to Shelley Mook?

48 HOURS: "Bad Boy" is produced by Chuck Stevenson, Michelle Feuer and Taigi Smith. Mike Baluzy and George Baluzy are the editors. Peter Schweitzer is the senior producer. Susan Zirinsky is the senior executive producer.

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