Peter Keeley, 56, was found dead near a beach at Broulee, about 20km south of Batemans Bay in February 2020.

Mr Keeley had gone to the region to meet one of three teenagers, all 17 years old at the time, who lured him from Canberra after they exchanged messages on dating app Grindr. Two of the three were acquitted in the NSW Supreme Court in June of murder.

While Mr Keeley was on his way, the teen he was to meet conducted an online search for "does holding a metal object in your hand make a difference to your punch?"

The three teens then discussed a plan for them to tie Mr Keeley and assault him.

A witness and authorities discovered the auctioneer's body in bushland near the beach, with his hands and feet tied.

Tape near his mouth was also found torn and removed.

The trio had pleaded not guilty to murder, with two facing a judge-alone trial in May while the trial for the third man had been set for November.

That trial is now vacated after he pleaded guilty on Tuesday to kidnapping Mr Keeley to assault him and thereby caused actual bodily harm.

His co-accused, prior to their trial and subsequent acquittal of murder, also pleaded guilty to aggravated kidnapping.

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A recorded police interview with one of the teens was played during the May trial. In it the teen told investigators the trio planned to only scare Mr Keeley "because we were all under the impression he was a paedophile".

He said they had "no concrete evidence" about that allegation and "I don't think there was any intention to kill him".

Forensic pathologist Dr Bernard I'Ons, whom the Crown relied on, concluded in his autopsy report that Mr Keeley died from craniofacial trauma and airway obstruction.

Dr I'Ons said Mr Keeley was concussed and in a prone position that led to asphyxia, contributing to his death.

Other factors for airway obstruction included Mr Keeley being gagged and having debris in his nose.

The cause of death was the major contention during trial. Specifically, whether it was from the assault or a possible methamphetamine overdose as the drug was detected in Mr Keeley's system at the time.

The defence argument, based on medical professor Johan Duflou's evidence, was that Mr Keeley's death "could reasonably be the result of methamphetamine toxicity" as he was a regular user of the drug.

Professor Duflou said the level of methamphetamine in Mr Keeley's system was "pretty much right in the centre [of where you would] expect" in the cases of an overdose.

Justice Michael Walton said the Crown's alleged cause of death had not been proven beyond reasonable doubt because the autopsy report "proceeded on a flawed premise".

In relation to the potential drug overdose, Justice Walton said professor Duflou's views should be preferred based on a number of factors, including that his "eminence on the question of methamphetamine toxicity is well recognised".

He said the Crown had also not excluded the possibility of a drug overdose as the cause of death.

On Tuesday, Justice Walton set August 24 for sentencing of the trio, but the legal parties may apply to change it if they need more time in relation to sentencing and medical reports.

AS IT HAPPENED

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