Police say they have clear evidence that shows Praween Chankhlai, 35, a former kamnan or subdistrict head of tambon Thakong in Nakhon Pathom's Muang district, ordered the shooting of a senior highway police officer at a dinner party at his house on Wednesday night.
Pol Gen Surachate Hakparn, the deputy national police chief heading the case, said yesterday police have the evidence and an investigation is underway. Police also know who helped the gunman and the suspect escape, and who destroyed the evidence, including CCTV camera footage and computer server data at the house.
At least four officers will be charged, he said, adding that a further probe will be conducted into the 25 officers who were at the event when the gunman killed Pol Maj Sivakorn Saibua, a local highway police station chief. Pol Lt Col Wasin Pandee, deputy commander of Highway Police Sub-division 2, was injured.
The gun was used by Thananchai Mamnak, 45, who fled the scene and was later killed in a gunfight while resisting arrest on Friday morning. Mr Praween surrendered to police on Thursday evening.
Pol Gen Surachate said that during the raid, a witness who lived in Mr Praween's house confessed that he buried the pistol near the reservoir of a waterworks agency in Muang district. Police yesterday took the worker to the spot, where they found a 9mm pistol wrapped in tablecloth from the dinner party. Forensic officers will examine the weapon.
The investigation team said the gun was acquired by a police officer in Nakhon Pathom under a police welfare gun scheme. Last month, the officer sold the gun to Mr Praween, who reportedly gave it to Thananchai.
Mr Praween denies any involvement and says the gunman acted independently. However, witnesses told police earlier that Mr Praween became angry after the victim rejected a request for a transfer for the kamnan's policeman nephew.
The Criminal Court yesterday approved a police request to detain Mr Praween. He will be detained until Sept 20 while police continue their investigation and the questioning of about 30 witnesses.
Under the law, a suspect can be detained for up to seven 12-day periods, or 84 days, before police have to press formal charges or let him go.
Police said earlier they would oppose bail for Mr Praween, noting the suspect had served as the kamnan of tambon Thakong for nine years, after his late father, also a kamnan.
Police said the suspect was an influential local figure who had cultivated ties with police from many stations. Officers of various ranks and other officials were regular guests at parties he hosted at his home. He also boasted close ties with politicians.
His wealth came from his ownership of two construction companies he inherited from his father. Records at the Department of Business Development show the businesses reported 2.6 billion baht in revenue over the past five years.
His luxury home has a swimming pool and a glass-enclosed garage that holds high-end cars, including a Bentley, a Mini Cooper and a Mercedes-Benz.
Police inspector-general Pol Gen Visanu Prasarttong-Osoth said the 25 officers present during the fatal shooting will also be investigated amid suspicions they may have supported illegal activities attributed to the wealth of Mr Praween. The most severe penalty could be expulsion from the police force. "They failed to perform their duty as policemen," he said.