Daniel Sancho Bronchalo, 29, appeared in court on Monday after being arrested on suspicion of killing Edwin Arrieta Arteaga, 44, a Colombian surgeon.
Details of the gruesome case first emerged last week when local media reported that body parts had been discovered around the island of Koh Phangan, a destination known for its lively parties and psychedelic retreats.
Sancho, a chef with a YouTube channel, initially reported the person missing, but later confessed over the weekend, according to Thai police.
He informed investigators that he had a confrontation with Arrieta last Wednesday, as Sancho wanted to end their relationship due to Arrieta's plans to marry someone else in Indonesia, explained Koh Phangan police captain Sucheep Chadakarn to NBC News.
Arrieta had threatened to cause trouble, and Sancho responded by punching him. Arrieta bit Sancho's hand, leading Sancho to strike his head repeatedly until he died, Chadakarn stated.
The Spanish news agency EFE reported that while admitting the crime, Sancho denied having a romantic involvement with Arrieta. "I am guilty, but I was Edwin’s hostage. He held me hostage. It was a glass cage, but it was a cage," Sancho was quoted as saying.
A family lawyer who visited Sancho stated to EFE, "I think he is relaxed. He knows what he did... He wants to plan how to live" in prison.
In Thailand, murder is punishable by death.
Sancho confessed on Saturday to dismembering the body into 15 pieces and guided the police to the locations where he had disposed of them, including a pier and a hotel, Chadakarn said.
Certain remains were discarded in the sea, while others were found in garbage pits. Additionally, soiled clothes were discovered last week, with four body parts washing up on the shore.
Sancho told the police that he purchased a kayak after the owner refused to rent it out on the night of the brutal murder, Chadakarn stated.
Thus far, investigators have recovered only seven pieces of the remains. DNA tests are currently being conducted to confirm their identity as Arrieta's.
Thai police collaborated with immigration officials to revoke Sancho's visa, according to Chadakarn.
Sancho is currently being held at Samui prison on Koh Samui Island following his court appearance, as police seek his continued detention while gathering more evidence for the trial.
Thai authorities have been in contact with the Spanish Embassy in Bangkok, Chadakarn added.
The embassy referred NBC News to the Spanish Foreign Affairs Ministry, which stated that due to data protection regulations, it couldn't reveal personal information about the accused.
"However, we can confirm that the Spanish Embassy in Bangkok is in permanent contact with the person concerned, with his family and with the local authorities, and that he is being provided with the consular assistance required in these cases," the ministry said in a statement.
Sancho is the son of Rodolfo Sancho and Silvia Bronchalo, well-known Spanish actors. His uncle, Felix Sancho, informed journalists in Spain that "A little respect for the family is all we ask for, because this is so painful," according to The Associated Press.
Colombia's Ministry of Foreign Affairs expressed gratitude to Thai Police for the investigation and offered condolences to the victim's family in a statement posted on its website on Sunday.