Police have seized security cameras, recordings and gambling equipment believed hastily removed from a gambling den where a shootout claimed four lives on Monday night.
The goods were found on Friday in three-storey shophouse opposite the building housing the casino.
Thung Mahamek police searched the premises and seized eight cameras, three hard discs, six gambling tables, 96 packs of cards and 500 gambling chips.
A baccarat table was earlier found dumped out the back of the casino building.
Acting Thung Mahamek police chief Pol Col Pitak Sutthikul said on Friday the shophouse was targeted after investigators questioned a man seen in a video, taken surreptitiously, showing the cameras and other equipment being removed from the room where the shooting occurred.
The gambling premises, in a building in soi 66 off Rama III Road in Yannawa district, were the scene of a bloody shoutout on Monday night. Four people were killed, including Pol Maj Watthanaset Samniangprasert of Samae Dam police station. According to his superiors, he was off-duty at the time.
The other victims were Thaworn Seesod, who is believed to have shot dead Pol Maj Watthanaset, and two women employees of the casino, Peeraya Noomlamoon and Cambodian Mao Salaepao.
Thaworn was the last to die, reportedly shot by Pipit Srisuwan, 61, alias Boy Bankrua, who claimed to be acting in self-defence.
Police would not confirm if the cameras were the same ones seen being removed from the crime scene. However, they were regarded as key evidence about what really happened that night.
Pol Col Pitak said investigators were still searching for other items believed removed from the crime scene.
Metropolitan Police Bureau (MPB) chief Pol Lt Gen Pakapong Pongpetra is under fire because the shootout exposed a gambling den said to have been operating for about 20 years and to be common local knowledge.
National police chief Pol Gen Chakthip Chaijinda gave him until Saturday to catch the second gunman.
Pol Gen Chakthip on Friday said he was serious about the warning he would transfer the city police chief out of the bureau if the shooter remained at large.
This only added to the confusion surrounding the events and the slow police response to the shooting.
Reports on Thursday said the alleged second shooter, Mr Pipit, had already surrendered, and he was quoted as saying he acted in self-defence.
But MPB deputy commissioner Pol Maj Gen Jirapat Phumjit said Mr Pipit was being sought under an arrest warrant on charges of murder.