Nearly 30 police officers were present when a highway police officer was shot dead last week during a dinner party at the house of an influential figure in Nakhon Pathom, whose business dealings are being thoroughly investigated, according to senior police.
Deputy national police chief Pol Gen Surachate Hakparn said on Monday that 28 police officers were at the house of Praween Chankhlai, chief (kamnan) of tambon Takong sub-district in Nakhon Pathom's Muang district. They were attending the dinner party there last Wednesday when a gunman fired multiple shots at Pol Maj Siwakorn Saibua, killing the 32-year-old highway police inspector on the spot.
Detectives previously believed 26 officers were at the crime scene but recently learned there were two more, Pol Gen Surachate said.
The 28 policemen were divided into three groups. One included those who brought Pol Maj Siwakorn and his injured supervisor to hospital. Another group helped the suspects, while the third fled the scene at once, Pol Gen Surachate said.
"It does not mean that those who brought the injured to hospital were innocent. We must find out exactly how many officers went to the hospital... If they lied, they will be held responsible for making false statements," he said.
Apart from the policemen, interrogators charged five civilians. One of them threw two CCTV servers from Mr Praween's house into water. Another buried the pistol used in the shooting and three others destroyed evidence at the scene by cleaning up blood stains and concealing spent cartridges.
Police would take about three days to retrieve data from the CCTV servers, Pol Gen Surachate said.
Sources said the Department of Special Investigation found that Mr Praween ran two construction companies which won bids for more than 1,000 projects worth about 3.5 billion baht from 2015 to 2022.
Pol Maj Gen Charoonkiat Pankaew, acting commander of highway police, said he would ask relevant officials to examine Mr Praween's business which also included trucks.
Pol Maj Siwakorn was honest in his suppression of truck overloading and declined to be lenient, the acting commander said.
Before the party, a supervisor of Pol Maj Siwakorn ordered him to attend the gathering to forge a reconciliation.
During the event, the murdered man was asked to transfer Mr Praween's nephew, a policeman, to a desired post but he rejected the request, Pol Maj Gen Charoonkiat said.
Mr Praween is suspected of having a gunman shoot Pol Maj Siwakorn to death. The former kamnan had already been sacked from his local administration position.
"Before his last breath, I touched his head and promised that his seniors and juniors at the Royal Thai Police Office will bring him justice," Pol Maj Gen Charoonkiat said.
Police and other organisations including the Revenue Department would examine the businesses and transactions of suspects in the case, he said.