That was until 3.38pm on a warm sunny day in May 1985 when, while driving home from a nearby shopping centre she stopped at the mailbox in front of the family house near Columbia, South Carolina to post a letter. At that moment, Shari Faye disappeared and was never seen alive again.
Only minutes later, her father, Robert, found her car at the top of the long driveway to the house. The door was open and the engine was running. Shari's handbag was lying on the passenger seat. But of Shari there was absolutely no sign.
After a frantic search, Robert Smith called the police. This sort of thing simply didn't happen in Columbia, a peaceful rural community which was proud to embody the very notion of family values. Sheriff Jim Metts, a former FBI agent, was a friend of Robert Smith and he instinctively knew this was no walkout after a family tiff.
Soon he had organised what was to become the biggest police manhunt in South Carolina history, assisted by over a thousand civilian volunteers. But to no avail. Shari Faye Smith had disappeared as completely as if she had stepped off the planet.
For three days the anguished Smith family waited for news. Then, that evening, came the first phone call. A man, obviously disguising his voice, claimed that he was holding Shari prisoner.
He told Robert Smith: "So you'll know this isn't a hoax. Shari had on a black and yellow bathing suit underneath her shirt and shorts," and added: "You'll get a letter later today." There was no ransom demand.
The two-page handwritten letter from Shari came by special delivery that afternoon. "Headed Last Will and Testament" it was a heartbreaking message full of love and fear and ended with the words: "I am sorry if I ever disappointed you in any way.
I only wanted to make you proud of me because I've always been proud of my family. There's so much I want to say that I should have said before now. I love you all and God bless. FBI agents Jim Wright and Ron Walker, now heading the inquiry with Sheriff Metts were deeply worried by the letter. They knew they were dealing with a sophisticated and extremely dangerous man and that Shari's life was in the balance — indeed, she could already be dead and her killer could be contemplating another similar crime.
They surmised that what probably happened was that the kidnapper had seen Shari out shopping and followed her home. Her tragedy was to have stopped at the mailbox, so allowing her abductor to pounce.
The following day there was a further call, this time taken by Shari's mother, Hilda. "Do you believe me now?" the kidnapper asked. "I need to know that Shari is well," Hilda said, to which the kidnapper replied: "You'll know in two or three days."
By now FBI experts had tapped the family's phone hoping to trace the kidnapper's calls but in 1985 "trap and trace" required keeping the caller on the line for at least 15 minutes and that was rarely possible. However a recording system had been set up so that the kidnapper's voice could be compared with other FBI voice-prints and hopefully identified.
The following evening the kidnapper called again and this time spoke to Shari's 21-year-old sister, Dawn, to whom he gave details of the kidnapping.
He had stopped his car when he saw her at the mailbox, had a friendly chat and then abducted her at gunpoint.
He was now prepared to release Shari the following day and told Dawn to have an ambulance standing by. He then gave explicit instructions to a location 20 miles away in neighbouring Saluda County.
It was there, on a wooded hillside, that police found the body of Shari Smith. She had been suffocated with duct tape over her nose and mouth. But of her killer there was no sign.
The Smith family heard nothing more until the day of Shari's funeral. Then in a call, again taken by Dawn, the killer said the abduction had got out of hand. He hadn't meant to kill Shari and now he was