A Thai court has sentenced an Australian man to death for the kidnapping and murder of a Hells Angels member alleged to have been a major drug trafficker.

Antonio Bagnato, 28, was found guilty of murder, deprivation of liberty and disposing of a body.

In December 2015, former Hells Angels member Wayne Schneider was abducted from outside his home by five men and later found buried with a broken neck and facial injuries consistent with a severe beating.

The judge said the killing was premeditated, with GPS from the getaway car, DNA from the crime scene and witness testimonies all connecting Bagnato to the crimes.

"The first defendant [Bagnato] is found guilty of all charges and according to the criminal code, the penalty is execution for the murder and deprivation of liberty, plus a year in prison for hiding the body," Judge Sirichai Polkarn at the Pattaya Provincial Court said.

The court room was packed with representatives of all parties.

"We've got hearts and they're hurting right now," a relative of Bagnato said, calling the verdict "ridiculous".

The judge said DNA evidence also placed 22-year-old American man Tyler Gerard at the scene of the abduction.

Gerard received a three-year sentence for deprivation of liberty that was reduced to two years for his cooperation with the investigation.

The sentence includes time already served in pre-trial detention, meaning he could be free before the end of the year.

Gerard's parents said they were relieved at the verdict.

"[Tyler's] words were, 'Calm down mum, pray for the other people in this room'," Tracy Gerard told the ABC.

Assault rifles, knuckledusters found in Bagnato properties

Wayne Schneider was found buried with a broken neck and facial injuries. ( ABC News )

Schneider was abducted from outside his luxury villa in Pattaya, Thailand in December 2015 by five men.

Melbourne underworld figure and former president of the Comancheros motorcycle gang Amad "Jay" Malkhoun was inside the house and told police he slept through the attack.

At a hearing in November, two security guards at Schneider's residential complex identified Bagnato as being involved in the kidnapping.

"I saw the defendant trying to push Wayne's legs into the cabin of the pick-up truck," Supan Pitakpong said.

Police tracked a GPS device fitted to the rented car used in the kidnapping.

Crime scene photos published in Thai media showed a bullet casing, an extendable baton rope and blood on the street where Schneider was abducted.

A search of properties rented by Bagnato found two assault rifles, two handguns, tasers and knuckledusters.

Bagnato's testimony differed markedly to that given by his co-accused. ( AAP: Facebook )

Baganto fled to Cambodia and was arrested in Phnom Penh five days later.

His version of events differed markedly to that given by co-accused Gerard and Australian Luke Cook, who was convicted last year of aiding a fugitive.

He told the court he left Schneider's house and spent the night with a Thai dancer from Pattaya's infamously sleazy Walking Street.

The judge said his alibi was not credible.

Bagnato told the court he was "scared" after Schneider's death and tried to get consular advice in Bangkok, but the Australian embassy was closed.

His account of getting a taxi and bus to Cambodia contradicted the court's previous ruling that Cook drove Bagnato, his wife and child to the border.

The whereabouts of the other three people involved in the abduction is unknown, although it is believed at least one man has returned to Australia.

Schneider's shrine in the yard of Angels Place, a bar run by the motorcycle club in Pattaya. ( ABC News )

Bagnato reportedly member of secretive fight club

Bagnato was a member of the Saint Michael Christian Brothers Fight Club — a secretive organisation that ran fight nights and required members to swear an oath of allegiance, according to Fairfax newspapers.

Bagnato was a member of the Saint Michael Christian Brothers Fight Club. ( AAP: Facebook )

Australian police had a warrant for his arrest in relation to the murder of Bradley Dillion in Sydney in 2014.

Bagnato arrived in Thailand two days after Dillion's murder.

He told the Thai court in November he earned about $11,000 a month training Muay Thai fighters in Pattaya.

Thai police told the ABC both men were on a watchlist for drugs and money laundering in Australia.

Thailand is a key transit country for organised crime syndicates — including various Australian bikie gangs — smuggling methamphetamine and heroin from the "Golden Triangle" to lucrative markets including Australia.

"It's a picture of a superhighway," Narcotics Suppression Bureau Chief Police Lieutenant General Sommai Kongwisaisuk told The Bangkok Post newspaper.