
Last month, four suspects in tapioca trading firms were arrested in Ubon Ratchathani province. Further investigation found up to 20 government officials were also involved.
The DSI is also gathering more evidence against a couple suspected of collusion in bidding on the government's free schoolmilk project.
The two are the first suspects to be arrested in the case.
The DSI is also looking into whether the milk supplied by the couple was up to standard.