Mr Schantz died after his throat was cut by Söderlund’s compatriot Johan Sebastian Ljung in The Lantern apartment complex in Koh Kaew, following a dispute about a Pattaya boiler room scam all three were involved in.
On January 24 this year Ljung was sentenced to life in prison for murder.
Both had pleaded not guilty, telling the court that Mr Schantz had struggled as Ljung held a knife to his throat, and that the killing was accidental.
Their defence lawyer, Phychaya Titapattawong, told The Phuket News after this morning’s hearing that the court had decided on the guilty verdicts after police introduced evidence that the duo came equipped with a knife, a handgun, a strip of rubber for restraining their victim, and a woolen ski mask.
When arrested, they had also confessed initially to murder, which Mr Phychaya said was a mistake on their part.
He said that he had already filed an appeal on behalf of Ljung and would do the same for Söderlund as soon as possible.
Ljung has already been transferred to Nakhon Sri Thammarat Central Prison and Söderlund will follow him. The appeal hearings will be held there.