A Sydney man who was found dead with his hands tied behind his back at Otford had driven to the remote location with two men he had met recently on a gay social networking site.
The body of Jarrod Dark, 45, was discovered by police shortly after midnight on Tuesday on a walking track leading to Werrong Beach, a nudist beach also known as Hell Hole Beach, in the national park near Otford, south of Sydney.
It is understood Mr Dark, from Fairfield in Sydney's west, was found with his hands tied behind his back with his own belt.
Police said Mr Dark had travelled to the location with two men, aged 43 and 37, whom he had met on a social media site. Fairfax Media understands that site was a gay social networking site, and the trio had met up a number of times recently.
Detective Inspector Tim Beattie, the crime manager at the Wollongong local area command, said the men had known each other for "a short period of time". He said the trio had travelled from Sydney together in the same car on the night of Mr Dark's death.
Detective Inspector Beattie said the two other men later told police they were forced to restrain Mr Dark after he became violent.
"They parked the car, walked up the track and continued on to the highest part of the track near the cliff face, and that's where the altercation allegedly took place," Detective Inspector Beattie said.
The track leads to the Werrong Beach, but the location where Mr Dark was found is at least a kilometre from the beach up the escarpment.
Following the alleged altercation, the two men told police they left Mr Dark in the national park and drove away.
They are understood to have flagged down a police car about 8.20pm on Monday to report what had happened.
They were taken to Canterbury Hospital to be treated for head injuries they allegedly suffered during the fight in the national park.
Wollongong police began searching the walking track that night and found Mr Dark's body about 12.15am on Tuesday.
A post-mortem was carried out on Wednesday but did not determine Mr Dark's cause of death, police said.
No arrests or charges have been laid over Mr Dark's death, and the police investigation is ongoing.
Police have urged anyone with information about Mr Dark's death to contact Crime Stoppers on 1800 333 000 or visit the Crime Stoppers online reporting page.