Kidnap Victim Didn't Flee For Four Years. Why?

I said before that children will believe a lie an adult tells them. What was the lie the man who kidnapped those boys told them?

Kidnap victim Shawn Hornbeck was "brainwashed" into staying with his abductor after being told his parents no longer wanted him.
His kidnapper also threatened to shoot the 15-year-old after snatching him off the street.

Is there a punishment severe enough for this kind of crime? As a mother, I can't think of one.