Former national police chief Somyot Poompanmoung reported to the Department of Special Investigation on Thursday for questioning about his "borrowing" 300 million baht from the owner of Victoria's Secret Massage parlour while in office.
Pol Gen Somyot met DSI interrogators at the division handling human trafficking cases in Bangkok.
The DSI summonsed him to provide information on his financial transactions involving Kampol Wirathepsuporn, the fugitive owner of the massage parlour.
Pol Gen Somyot, currently president of the Football Association of Thailand, did not talk to news reporters before going in for questioning.
Pol Lt Col Supat Thamthanarak, DSI director for human trafficking cases, said Pol Gen Somyot would testify as a witness in a human trafficking case relating to Victoria's Secret Massage parlour.
Questions would focus on financial transactions and the 300 million baht Pol Gen Somyot borrowed from Mr Kampol.
The retired police chief earlier admitted he had borrowed the money from Mr Kampol, and said they had been friends for two decades.
Mr Kampol and his wife remain at large. Authorities allege the massage parlour had many underage girls who were forced to provide sex services.
The parlour, in Huai Khwang district, Bangkok, was raided on Jan 12. Investigators later uncovered the financial transactions between Pol Gen Somyot, when he was police chief, and Mr Kampol.
