The suspected mastermind of last month's deadly bomb attack in Thailand left Bangladesh 12 days ago, and efforts in Malaysia to track the man suspected of planting the explosives have been unsuccessful, Thai police said on Friday.
No group has claimed responsibility for the Aug. 17 attack at a Hindu shrine in Bangkok, which killed 20 people, including 14 foreign tourists, among them seven from Hong Kong and mainland China.
The man investigators believe organised the plot and fled on the eve of the blast spent two weeks in Bangladesh before flying out of Dhaka on Aug. 30. He had stated in an exit document his final destination was Beijing, via New Delhi, police said.
"He recorded on his departure card that he would transit in Delhi to go to China," police spokesman Prawut Thawornsiri said.
"In the end he didn't go to China. He went somewhere else."
Prawut did not say where the man police are referring to by his alias "Izan" had gone. He said he received the information from Bangladesh's ambassador in Bangkok.
Chinese Foreign Ministry spokesman Hong Lei said he was not aware if the suspect had flown to China.
Thai police have ruled out international militants as responsible for the attack but have not said why nor what they believe the motive was.
Their investigation had expanded to Malaysia, police said, following a lead that a yellow-shirted man caught on a security camera leaving the bomb at the Erawan Shrine may have crossed Thailand's southern border.
Suchart Teerasawat, a police inspector general, told Reuters he was in Malaysia last week but had found nothing.
Police also said they were following a money trail that connected bank transfers to the purchase of bomb materials.
"We have evidence of the shops where this was spent and what was bought," Seehanat Prayoonrat, secretary-general of Anti Money Laundering Office, told reporters. He said details were being withheld so not to endanger inquiries.
The investigation gained momentum with information from one of two detained suspects, who was arrested with a Chinese passport bearing the name Yusufu Mieraili.
He admitted to giving a bag containing the device to the bomber and said another man, Abu Dustar Abdulrahman, alias Izan, had given orders to the plotters.
Thai visas were issued in Kuala Lumpur to both men, according to a diplomatic source, using Chinese passports with names Abu Dustar Abdulrahman and Yusufu Mieraili, in October 2014 and February 2015 respectively.
The use of Chinese passports, at least one of which stated Xinjiang as a birthplace, adds fuel to speculation the bombing may have been revenge by sympathisers of Turkic-speaking Uighur Muslims. Uighurs are from the Xinjiang region.
Thailand was widely condemned in July for forcibly repatriating 109 Uighurs to China, where they say they are persecuted, an accusation Beijing rejects.