The DSI questioned Panitan Wattanayagorn, former secretary and spokesperson for the then government of PM Abhisit Vejjajiva, because Panitan was involved in meetings with the now-defunct Centre for the Resolution of Emergency Situation (CRES).
The DSI said it needed more time to scrutinise all of the 92 fatalities and many investigations were still ongoing.
The DSI deputy chief said it might also request TRCT chairman Kanit na Nakorn to answer some questions and check how 'reliable' the report was.