Timothy Nicholls, now 33, was dragged into a toilet block in suburban Brisbane on December 5, 1987, and repeatedly raped until a childcare worker came looking for him. Cowan, who was sentenced to two years in jail for the attack, was undertaking community service work next to a childcare centre as part of his punishment for breaking, entering and stealing.

''I told him I was going to tell my mum and he started to strangle me,'' Mr Nicholls told 60 Minutes on Sunday night. ''Like he threatened he was going to kill me. He grabbed me by the throat and if I didn't do it I thought I was going to die.''

''I was a bright student and after that, my schooling, my, my attitude, my happiness was, didn't have it no more. He took everything. He took my life.''

Cowan was sentenced on Friday to life in prison for the abduction and murder of Sunshine Coast schoolboy Daniel Morcombe, 13, in 2003.

Daniel's parents, Bruce and Denise Morcombe, revealed on 60 Minutes that they almost flew to Perth to find Cowan in 2011 following a coronial inquiry into their son's disappearance because they were so sure he was Daniel's killer.

Cowan had a shocking record of paedophilia and a hole in his alibi but he told the inquiry he would not have taken Daniel because he liked boys that were six or seven years old, not 13.

''We just went, 'Oh my god, you've got to be joking','' Mrs Morcombe said. ''The police knew all this as well. I mean, after the coronial we nearly flew over to Perth … to find him but luckily we didn't because we didn't know the covert operation had started a few days beforehand.''

One of the country's largest and most elaborate sting operations eventually elicited a confession from Cowan, who told undercover police that he had abducted Daniel from a bus stop, strangled him and buried him in bushland.

The Morcombes told 60 Minutes that if a public register of paedophiles had been in place at the time, their son would be alive today. They said Cowan had been a ''demon'' for nearly 30 years.

''I think once they've offended the first time and been charged and found guilty for that offence, they should be on the register from day one,'' Mrs Morcombe said. ''No second chance.''

A former girlfriend of Cowan's told the program about the night he abducted a six-year-old boy from a Darwin caravan park in 1993 and raped him. He left the boy for dead with horrific injuries but the child survived.

''For days we thought he'd been hit by a car… Then word got around that something more sinister had happened,'' the woman said.

The boy, now 27 years old, told Channel Seven’s Sunday Night that he was "angry" when he learnt that Cowan had killed Daniel.

"Because he shouldn’t have got out when he did it to me," he said.

He recalled being tied up in the boot of the car but being able to wriggle free from the ropes.

"I think I had the will power to survive," said the man, who Channel Seven only identified as David.

Cowan was sentenced to seven years in jail for the assault.