Queensland teenager Daniel Morcombe was allegedly killed as he fought off a sex attacker who had approached him at a bus stop.

Sunshine Coast schoolboy Daniel Morcombe was brutally killed while struggling to escape from a random, opportunistic sex attack, a jury has heard.

The trial of the teen’s accused killer was told the most detailed – and chilling – description so far of Daniel’s final moments in December 2003.

Jurors have previously watched Brett Peter Cowan confess to the murder in a secretly filmed conversation with an undercover police officer.

The Supreme Court jury on Monday heard Cowan outline in detail how he allegedly abducted Daniel, took him to an abandoned house and snapped his neck when the 13-year-old boy resisted his sexual advances.

In 2011, Cowan took undercover police posing as criminal gang members to the Sunshine Coast road where he said he spotted the “cute” teen waiting for a bus.

The covert officers had persuaded Cowan to retrace his steps under the pretence of cleaning up evidence.

“When the bus drove past he was like ‘what am I gonna do’ and I offered him a lift,” Cowan said in the secretly recorded conversation played to the court on Monday.

“I really don’t know what I was thinking … you know I’m an opportunistic offender.”

Daniel’s parents and one of his brothers listened to the recording from the public gallery in Brisbane as Cowan outlined how he’d driven Daniel to an isolated, abandoned demountable house in the Sunshine Coast hinterland.

The teen accepted Cowan’s explanation he needed to “duck home” but cried ‘oh no’ when Cowan lured him inside the house and pulled his pants down.

“I thought he was going to run and my arm went around his neck and I choked him out,” Cowan said.

“I actually felt that break … that bone that’s in there, I felt that snap in my arm when I pushed it.”

He’d said he’d intended to take the teen back to the shopping centre after assaulting him but feared he’d be caught if he let him go.

Cowan described dumping Daniel’s body in nearby bushland and tossing his clothes in a creek.

He’d brushed away his car’s tyre marks with a branch and later burned his own clothes.

When police questioned him over the teen’s disappearance weeks later Cowan said he thought he was “gone” but just “stuck to my story”.

“My palms were wet, dripping wet with the stress of it,” he said of being grilled by lawyers at a 2011 inquest into Daniel’s disappearance.

He told undercover police only they knew his secret and “that’s how far it needs to go”.

Cowan, 44, has pleaded not guilty to murder, indecent treatment of a child and interfering with a corpse.

The trial continues.