Mr Mark Cheng Jin Quan was supposed to be on a one-day trip to Thailand on Jan 9, but he ended up being held captive, drugged and tortured in a kidnapping that was allegedly masterminded by his travelling companion, fellow Singaporean Kim Lee Yao Wei.
"I was shocked. I thought we were good," the 32-year-old said, referring to Lee.
He spoke to The Straits Times in a phone interview four days after he managed to escape his captors. He said he was in a safe house provided by the Thai police on Tuesday .
It never struck him that Lee would be the alleged mastermind behind his ordeal, and he learnt this from the Thai police only later on.
"I thought he was kidnapped too," Mr Cheng said.
His trip had started normally enough. He and Lee arrived in Bangkok on the morning of Jan 9 and took a Grab taxi from Suvarnabhumi Airport to meet a contact of Lee's for a "social visit".
"I didn't know where we were going. I trusted him completely. We were on a trip together before," said Mr Cheng, a former blockchain adviser with Singapore fintech company X Infinity.
He said he met Lee a few years back, but they became closer only over the past year when Lee wanted to learn more about bitcoin mining.
After they had been on the road for about an hour, they stopped at a petrol station in Suwintawong Road in Chachoengsao province to buy groceries and to use the restroom. Mr Cheng said it was then that he was grabbed by a group of masked men, blindfolded and bundled into a car.
"I was forced to drink some orange juice. Then my lips went numb," said Mr Cheng, who added that he did not pass out.
He later found himself held at a house that was in the Kabin Buri district of Prachin Buri province, some 135km east of Bangkok. His legs were tied to a chair and his hands were bound together, he said, and he was kept blindfolded most of the time.
He told Chinese-language evening daily Lianhe Wanbao that he was taken to four locations in forested areas, where he was tortured for 12 hours.
According to Mr Cheng, there was one main captor who spoke to him in English, but at times he heard other voices speaking in Thai.
Mr Cheng said he was still blindfolded, but he heard the sound of digging and the gun cocking. His kidnapper told him he would be buried there. But he managed to loosen the strings that bound his wrists and knocked the gun out of the kidnapper's hand and punched him before fleeing.
He said his kidnappers beat and electrocuted him with electrical wires while demanding he pay his ransom of US$500,000 (S$674,000) in bitcoin. Mr Cheng transferred over 5.9 bitcoins that he and his friends owned, worth 1.4 million baht (S$62,300).
The captor then allegedly forced him to call his mother and friends to get more money, but no one answered as it was past midnight.
Apparently dissatisfied with the amount they got, the group took Mr Cheng to another location, where they threatened to kill him. He said he was forced to kneel on a grass patch and had a gun pressed against his head and then put into his mouth.
Mr Cheng said he was still blindfolded, but he heard the sound of digging and the gun cocking. His kidnapper told him he would be buried there. But he managed to loosen the strings that bound his wrists and knocked the gun out of the kidnapper's hand and punched him before fleeing, he said.
He found his way to a road and hitched a ride on a motorcycle to a police station. By that time, the sun had begun to rise.
Lee, 31, was arrested at a Bangkok hotel on Sunday and has been charged with robbery, detention of others, physical assault and illegal possession of firearms.
He confessed to all charges.
Chachoengsao police told The Straits Times that the charges could amount to a life sentence.
Police identified the owner of the black Ford Ranger pickup allegedly used to kidnap Mr Cheng, from security footage from the petrol station. Mr Cheng said he was shown police photos and recognised the owner as 24-year-old Thai-German actor Chano Pemberger, whom he met once last year at a friend's birthday party in Thailand. Mr Chano is being investigated by police.
Police have also recovered about 1.2 million baht found in the bank account belonging to Lee's Thai girlfriend, the proceeds from the sale of Mr Cheng's bitcoins.
They returned the money to Mr Cheng, said Police Major-General Chakrit Sawasdee, Chachoengsao's police chief. However, Mr Cheng claimed that he had not received the ransom money.
Mr Cheng, a co-founder of the now-defunct Avelife Foundation, which focuses on social enterprise and the environment, received an award from Queen Elizabeth II in 2016 for his work in protecting the environment.
However, he was slapped with four charges last year, according to legal documents seen by The Straits Times. He was accused of misappropriating $323,052 belonging to an investment company in 2014.
According to The New Paper, Mr Cheng was released on bail and allowed to travel to Thailand and Malaysia for work. His next court hearing is on Feb 3, which Mr Cheng said he intends to attend.
"I don't think I want to come back here (to Thailand) again," he said, adding that he will leave Thailand either today or tomorrow.
However, he is expected back in Thailand to testify at Lee's trial some months later.