A police officer was killed, along with three others, in the shootings at the illegal casino on Rama III Road.
The surrender came after national police chief Pol Gen Chakthip Chaijinda ordered city police commissioner Pol Lt Gen Pakapong Pongpetra to catch the suspect before Sept 10 or face a transfer to an inactive post, reports the Bangkok Post.
The order was announced by Pol Col Kissana Phathanacharoen, deputy spokesman of the Royal Thai Police.
Pol Lt Gen Pakapong was also ordered to explain why the den had been allowed to operate.
The source identified the suspect by his alias, Boy Bankrua.
Boy contacted Bangkok police and gave himself up yesterday, telling police he shot dead Thaworn Seesod, 51, in self-defence.
Thaworn allegedly shot dead Pol Maj Watthanaset Samniangprasert, a 32-year-old interrogation inspector with Samae Dam police station, who was reported to have been gambling at the casino on the night of the killings.
According to the source, Boy, a den staff member, said Thaworn appeared agitated and was waving a gun. Boy said that although the gun was not pointed at him, he feared getting hit by a stray bullet, so he decided to shoot Thaworn first, the source said.
The source said the shooting of Thaworn occurred after he allegedly killed Pol Maj Watthanaset and two casino attendants, Peeraya Noomlamoon and Mao Salaepao, a Cambodian.
Police suspect a gambling feud drove Thaworn to kill Pol Maj Watthanaset. CCTV cameras were removed from the venue, prompting speculation about who was involved. It was reported that local police arrived at the scene before forensic experts were sent in the following morning.
Pol Maj Saharat Saksilpachai, deputy chief of the Metropolitan Police Bureau, said yesterday the investigation team handling the case was instructed to find out who removed the cameras, and insisted he was not concerned about reports saying a police official ran the casino. A video of men seemingly removing cameras at the illegal casino surfaced on social media yesterday.
“Remove all [cameras],” a man says in the video. “Use pliers to cut all electrical wires,” another says.
The footage, apparently captured by a hidden camera, shows men clearing equipment and a bloodstained Baccarat table being dumped behind the den.