David, 40, said that he intends to appeal. So does the other convicted man, Lajos Gyorgy Kvalka, 50.
David was arrested soon after at an ATM at the MBK shopping centre in Bangkok. Kvalka surrendered to Tourist Police on Samui and was brought back to Phuket.
The killing of Peter Reisz, 47, took place on November 24, 2012 at a house in Phanason Residence, close to Central Festival Phuket.
Kvalka admitted helping David clean up the blood and dispose of the body, dumping it near a pond in Phuket's Kathu district. But he said he played no part in the bludgeoning and stabbing of Reisz.
David believed Reisz swindled him out of 15 million baht in a property deal that went wrong.
Once the murder case on Phuket concludes, David will be sent back to Samui where he faces another murder charge of killing Hungarian billionaire Laszlo Csepai.