He was arrested by immigration police on his return from Hong Kong.
The 38-year-old businessman is one of the four suspects allegedly linked to the Macao 888 online gambling website.
Chaiwat is the eldest of four brothers recently accused by actress Arisara “Due” Thongborisut in a Facebook post of running an online gambling website. In her post, she hinted that all the brothers had nicknames starting with “B”.
The suspect was taken to Cyber Crime Investigation Bureau (CCIB) office in Nonthaburi province at 11pm for more than an hour of interrogation.
The suspect's lawyer, Phisit Chutipornpongchai, told the press after meeting with CCIB investigators at 12.30am on Wednesday that Chaiwat faced a hard time during interrogation on his alleged Macao 888 financial transactions.
"Chaiwat became stressed during the interrogation," he said, adding that he was also suffering from an underlying disease.
He added that the police had not questioned Chaiwat about physical assault on Arisara, the suspect's ex-girlfriend.
"Chaiwat denied being involved in the Macao 888 online gambling website," he said, adding that the suspect is ready to fight the charges against him.
He added that there were no bail negotiations as it was a criminal case.
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