Police have arrested a third suspect over the gruesome murder of a gangland-linked German in Thailand.

Pakistani national Zahrouk Kareem Uddin, 27, was caught in Kanchanaburi province on Wednesday night following the murder of shady German ex-pat Hans Peter Walter Mack, 62, who was found chopped into pieces inside a freezer in Pattaya on Monday night.

Cops previously detained the other two suspects, alleged motorbike gang member Olaf Thorsten Brinkmann, 52, and obese German female property agent Petra Christl Grundgreif, 54, on Tuesday night.

The stocky tattooed suspect Zahrouk had checked into a hotel in the province, near the border with Myanmar, but was reported to police by the owner who had seen him on the news.

Police Major General Pairoj Khumpai, the commander of Kanchanaburi Provincial Police, said: 'The suspect had taken a taxi to Kanchanaburi. It is possible he intended to cross the border to Myanmar to escape.'

Footage shows officers frogmarching Zahrouk to the Kanchanaburi police station for interrogation.

During questioning, the large-built man was described as 'stressed and trembling' and allegedly denied his involvement in the crime. He also requested to speak with a lawyer and his family, police said.

Zahrouk's parents, both seafood importers in Phuket, said they had met the suspect Petra Christl Grundgreif two years ago when she partnered with them to transport products in Pattaya. They said they cut ties with the German because she was 'unreliable' and placed orders without paying.

The couple later found that their son Zahrouk was still in contact with the woman for a property business, and said they tried to discourage him from dealing with her until news of the murder emerged.

The Pakistani man's emotional family said they believed in Zahrouk's innocence, adding he would cooperate with police.

Police Major General Pairoj said they are coordinating with Tourist Police for a translator for easier communication.

Meanwhile, police have also seized an 18ft Yamaha speedboat from alleged killer Olaf Brinkmann's house in Pattaya.

Detectives said a German informant had called them, saying he was asked by Olaf to dock the vessel at the Ocean Marina Jomtien in Pattaya on July 9. He was unable to do so because of insufficient documents, he said.

Officers later found footage of Zahrouk and Olaf shopping for fishing equipment in the region. Investigators said the suspects may have planned to dump the victim's body in the sea.

Zahrouk has been handed over to the Mueang Kanchanaburi Police station and was scheduled to be taken to the Nong Prue Police Station, where investigators are handling the care.

Meanwhile, the other two suspects Olaf and Petra were detained in police custody on July 11.

The deceased Hans had been living with his glamorous and much younger Thai wife Piraya Boonmak, 24, for around five years in Pattaya. He had two sons from his previous wife.

He was reported missing on July 5 when he failed to return home. His Mercedes-Benz coupe was found several days later, but its interior had been wiped with cleaning solvent allegedly 'to destroy evidence'.

Police are yet to comment on the German's background and the deals he was involved with but police chief Surachate Hakparn has now vowed to rid the country of foreigners linked to crime, like Hans was.

In February 2018, Hans was arrested in Pattaya along with a Thai woman Amornrat Kateuy on charges of allegedly prostituting girls under the age of 18.

The ex-pat was allegedly put under surveillance by police before being seen with Amornrat taking a 17-year-old girl to a house.

Officers raided the home where they allegedly found the German sitting with the teenager while a shirtless foreigner emerged from a bedroom where the 15-year-old was wrapped only in a towel.

The girl told police that the foreigner had paid her for sexual services and that Amornrat and Hans had taken her there to perform the service.

Police investigated Hans and Amornrat for human trafficking and procuring a sex service provided by an underage girl.

The man caught with the girl was charged with sexual activities with a minor.

It is not known how Hans avoided further police action and what came of the case.