Media reported on Friday that Mr Setthawut was the land official who surveyed and prepared the issuance of title deeds for 18 blocks of land near a cliff on Nong Chuem mountain in Khanong Phra sub-district of Pak Chong district, Nakhon Ratchasima.
The land area totalled 528,000 square metres and was originally allocated to 11 poor people so they and their families could make a living in 2002. The title deeds were issued in 2007.
Although the recipients were not allowed to sell the land for five years, they leased it to Ban Chum Thong Co during that period and afterwards sold it to the company.
Later the company sold the plots of land to high-ranking police officers. Several mansions were built there and reportedly now belong to senior police officers, public prosecutors, university lecturers and politicians' relatives.
The Office of the Public Sector Anti-Corruption Commission (PACC) and the 2nd Army have investigated their possession of the land and found out it actually belongs to an infantry centre in Lop Buri province. Action is now being taken to retrieve the land.
Thanawat Sanitsakdee, an investigator of the PACC, was quoted as saying that a police major-general built a mansion there in 2010, well before the title deed to the land plot could have been transferred.
He said he would next week propose the revocation of the title deeds and ask the Anti-Money Laundering Office to seize the assets on the land.