Daniel Sancho Bronchalo was convicted of killing Edwin Arrieta Arteaga, from Colombia, on Koh Pha-ngan in southern Thailand, last August.

Bronchalo, 30, is the son of Rodolfo Sancho Aguirre, a prominent Spanish actor, and Silvia Bronchalo, also an actor. Both were in court for Thursday's verdict.

Sancho told his trial that he acted in self defence when Mr Arteaga tried to sexually assault him.

He claimed they got into a fight and the 44-year-old fell and hit his head on a bathtub, losing consciousness and then dying.

He had denied premeditated murder - but admitted dismembering the body and disposing of the parts on land and at sea.

Surveillance video obtained by police showed Sancho allegedly purchasing a knife, rubber gloves, garbage bags and cleaning solutions at a convenience store before Arrieta's death, which prosecutors claimed bolstered the charge of premeditated murder.

Police had claimed that Sancho had confessed to the murder, saying he had planned it because Mr Arteaga threatened to disgrace him and his family by revealing their alleged sexual relationship.

In his closing statement earlier in his trial, Sancho told the court he regretted his actions, the Spanish newspaper El País reported.

"I am sorry that a life has been lost and that parents have lost a son," Sancho said. "I am sorry that his family was not able to bury him properly. I'm sorry for what I did after the death."

For the charge of concealing or damaging a body, he received a four-month prison sentence, reduced by half because he confessed.

He had also pleaded not guilty to the charge of destroying another person's documents - the victim's passport - for which he received a two-year prison term.

The Koh Samui provincial court issued an initial sentence of death for Sancho, but commuted it to life imprisonment because he cooperated during the trial, according to police.

The elements of the case - violent death on a holiday island, the celebrity connections and the lurid details - made it a huge story in Spain, prompting HBO to produce a Spanish-language documentary on the events.

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Bussakorn Kaewleeled, a lawyer for the victim's family, said they were satisfied with the outcome.

Bussakorn told reporters outside court: "The plaintiff is satisfied with the sentence because he [Sancho] will be put in prison for life and they [the plaintiff] receive some financial compensation."