He based this on that fact the attack occurred on a holiday when the court was closed.
Police suspect the assailants came by car and were highly experienced in using a grenade launcher. A glass window was smashed in the attack. They will try to identify the suspects through security cameras.
Aek said there had been four M79 attacks since the anti-government rally started. One was at the Lat Phrao protest and another at Chatuchak market, which is under the jurisdiction of Bang Sue police.
There was also an attack at the Chaeng Wattana rally base, which is under Thung Song Hong police jurisdiction. The Criminal Court is under the jurisdiction of Phaholyothin police.
Based on ballistics, police believe different groups were responsible for each attack.