His family didn't see him again for four years and three months - until he was discovered living 80km away with Michael Devlin, a 41-year-old pizza parlour worker. What makes this one of the more remarkable child-abduction cases in US history is that Shawn, now 15, lived an apparently normal life with Devlin in his two-bedroom apartment in the St Louis suburb of Kirkwood.

Shawn rode his bicycle in the street, had sleepovers with neighbourhood children and accessed the internet.

Last week as he appeared with his parents on the Oprah Winfrey show and more details emerged one unanswered question hung over the story: Why didn't he try to escape?

Just over a year ago, at 1.59am, Shawn posted a message under the name "Shawn Devlin" on the missing-child website Shawn's parents, Pam and Craig Akers, had set up, called ShawnHornbeck. com. He asked: "How long are you planing to look for your son?"

Then at 2.56pm the same day, he posted another message, asking if he could compose a poem for the family. The poem never appeared.

The most common explanation for the child's behaviour is Stockholm syndrome, a condition in which hostages identify with their captors.

But not everyone is convinced, and the Hornbeck family have had to cope with rumours. Was Shawn really kidnapped, or did he run away?

The Fox News talk show host Bill O'Reilly voiced the thoughts of some: "You know the Stockholm syndrome thing, I don't buy it." Shawn accepted his captivity because Devlin made life easy for him, O'Reilly claimed. "No school, play all day long."

Shawn's only media appearance has been on the Oprah Winfrey show. Holding both his parents' hands, he appeared withdrawn and quiet. He thought about his parents every day for the past four years, he said. "I prayed that one day my parents would find me and I'd be united."

The message to his parents' website was an attempt to send a signal. "I was hoping it might give some kind of hint, " a subdued Shawn said. His stepfather said he remembered the message but did not suspect it was from his son. His parents said they were all undergoing therapy and had been advised not to press Shawn for the details of his captivity. They just nodded when asked if they believed he had been sexually assaulted. His stepfather said he believed that "there has to have been something held over his head" to stop him escaping or contacting his parents.

Winfrey said that one of the conditions of obtaining the interview was that she would not ask about details of his captivity, or why he had not tried to escape, but after the interview, she had asked him in private why he had not tried to escape. He replied that it was because he was "terrified". Devlin was charged in Washington County for the 2002 abduction of Shawn.