The Pattaya Provincial Court delivered the death sentence to Shahrukh Karim Uddin, a Thai of Pakistani descent, on Friday for the murder of Peter Ralter Mack, 62, in July 2023, the Bangkok Post newspaper reported.
Mack's dismembered body was found inside a freezer covered in a thick layer of tape at a residence in an outer Pattaya suburb in southern Thailand's Chonburi province.
German nationals Olaf Thorsten Brinkmann and Petra Christl Grundgreif confessed to the crime during the trial and their sentences were reduced from capital punishment to life in prison as a result.
All three defendants were found guilty of premeditated murder and concealing a body.
Mack disappeared after telling his wife he was meeting another property realtor, although his family later believed he had been lured away and kidnapped.
The court heard evidence that the group planned to dispose of Mack's body at sea and transferred 3.35 million baht ($98,000) out of his account.