Updated ,first published
Singapore: Australian Simon Carman will “most likely” be sentenced to death if convicted of the killing of teenager Thanchanok Donhomla, after which time his life will hinge on the grace of Thailand’s all-powerful King Rama X, according to a Thai justice expert.
Carman is detained in Pattaya, about 150 kilometres south of Bangkok, charged with murdering the 17-year-old on Thursday last week and stuffing her body into a suitcase that he later discarded near railway tracks.
The pair had earlier “agreed to engage in sexual services”, according to the official police report.
Ronnakorn Bunmee, assistant professor of law at Thailand’s Thammasat University, said the allegations, as they were presently being reported, did not augur well for the Ballarat-born 45-year-old.
“If a guy kills a girl and conceals her body, and then tries to flee the country without showing any sign of remorse … that would be considered as section 289(5), which means you murder someone in a cruel, torturous manner, and that carries a mandatory death sentence,” Bunmee said, citing Thailand’s criminal code.
Photos have emerged revealing the slovenly state of the apartment Carman had been renting since the beginning of the year for $330 a month – and where police allege the murder took place. The images show empty spirits bottles, WD-40 and bottled water perched on a small table and fridge. Piles of clothes cover the furniture.
Taken on Friday after Thanchanok went missing, but before her body was discovered, the photos also show one of her unnamed friends speaking with the alleged killer.
Carman left for Bangkok’s Suvarnabhumi Airport about half an hour later, according to one of the timestamps and the investigators’ timeline of events.
Immigration officials arrested him at the airport on Friday evening, just minutes before he was about to board a flight home, according to Pattaya City Police Colonel Anek Srathongyoo.
Srathongyoo said Carman initially denied killing Thanchanok, then changed his story to self-defence – she had come at him with a knife, he claimed – when presented with damning CCTV footage showing him leaving his accommodation with the suitcase and returning without it.
Bunmee said self-defence was a valid type of defence, but Carman would have to demonstrate it was reasonable and proportionate.
Carman’s neighbours said one of the most noticeable things about him was his slow speech and movement, which he told them had been caused by a brain tumour. One of the photos from inside the apartment showed a significant scar on the back of his head.
“If he can prove that because of his injury, because of his mental health, or anything, that he cannot differentiate between the right and wrong … that would be a mitigating factor,” Bunmee said. “But if you cannot differentiate between right and wrong, why on earth do you try to conceal the body?”
The upshot was that Carman would probably get a death sentence if convicted, he said. But it was also likely that King Vajiralongkorn, or Rama X, would follow precedent and commute the sentence to life imprisonment. After 15 years, the monarch could again use his personal discretion and consider an application for release.
Pardons were usually granted on significant national days such as the king’s birthday and the queen’s birthday, but not always.
The most recent execution, by lethal injection, was that of Theerasak Longji in 2018. The 26-year-old was found guilty of stabbing a boy 24 times in 2012 and stealing his phone. In that case, the victim was also 17.
The king did not grant Longji clemency.
Had Carman made it home on that Friday night flight, he would most likely have avoided any chance of execution without needing to rely on Thailand’s king – even if he had been extradited.
“In the case of Thailand, I think because they still impose the death penalty, that’s where the governments of each country [would] have to negotiate …” WA Police Commissioner Col Blanch told Radio 6PR on Wednesday.
“Generally speaking, the death penalty would have to be off the table for any agreement of extradition. That’s been the case for some time in Australia, and that’s because we obviously don’t have the death penalty here, and we can’t accept that as a penalty, even for the most serious of crimes, which is murder.”
According to Amnesty International, Thailand handed down 119 capital sentences in 2025, including seven to foreign nationals.
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