Police investigators are questioning a man in relation to the Aurora gold shop heist in Lop Buri, said national police chief Pol Gen Chakthip Chaijinda on Sunday.
At a media briefing on progress into the case, Pol Gen Chakthip said he was informed by his deputy, Pol Gen Chaiwat Kateworachai, that a man who resembles the robber was being questioned in Nong Khai.
The man was also carrying a bag similar to the one carried by the suspect, he said.
The national police chief did not go into detail and stopped short of saying where the man was found or what he was doing when he was apprehended. Nor is it clear if he is cooperating.
"Our investigators have the skills to question this suspect. If he is not the robber, he will be freed. That's it," he said.
Pol Gen Chakthip had earlier said investigators have narrowed down their search as they believe the robber may have fled abroad through a land border crossing.