Thai police are readying to charge an American man with the murder of former Hells Angels member Wayne Schneider.
Tyler Gerald, 21, who has been arrested, is believed to have been one of the five men who abducted the Australian man from his home on Monday.
Mr Schneider was found buried in a roadside grave with a broken neck and facial injuries on Tuesday, a day after he was abducted from his home.
Police in the seaside town of Pattaya, south of Bangkok, have also detained the 25-year-old female partner of Australian man, Antonio Bagnato, who is believed to have masterminded the attack.
An arrest warrant has been issued for Mr Bagnato, but reports say he has fled to Cambodia.
Police said the motive for the murder was a dispute between Mr Schneider and Mr Bagnato, whom he was seen drinking with on Sunday night.
They said both men were on a watch-list for drugs and money laundering in Australia, but there was no information about them dealing drugs in Thailand.
Police said Mr Bagnato asked his Thai partner to rent the vehicle used in the kidnapping – which was fitted with a GPS system that led police to the body – and then told her to delete all text messages relating to the car hire.
She has not been formally charged and is being held at a military base under wide-ranging powers introduced after last year’s coup.
Mr Schneider has previously been described as a senior member of the Hells Angels.
In 2006, Mr Schneider was on New South Wales’ most wanted list over the shooting of a bouncer in the kneecap outside a Kings Cross nightclub.
The charges were later dropped.
He has also faced charges for drug offences and dealing with the proceeds of crime, after being found with $200,000 worth of casino chips in 2009.