The case report on the alleged killing of a suspected drug dealer while in custody at Muang Nakhon Sawan Police Station last month has been submitted to prosecutors and is expected to be filed in court next week.
Former station superintendent Pol Col Thitisan Utthanaphon and six other officers are accused of killing Chiraphong Thanapat, a 24-year-old drug suspect while reportedly trying to extort money from him.
Pol Col Thitisan, also known as Joe Ferrari because he owns a collection of supercars, is the prime suspect in the case.
Footage of the alleged torture and killing of Chiraphong was posted online, sparking outrage and a storm of criticism against the police.
Sompong Yenkaew, deputy chief of Office of Public Prosecution Region 6, said investigators have wrapped up their probe into Chiraphong's death and forwarded their report to the office.
Mr Sompong said the report will be filed at the Nakhon Sawan Provincial Court next week so it can hold an inquiry and issue an official ruling on Chiraphong's death.
The prosecution is scheduled to forward the case on Tuesday, he said.
According to the report, Chiraphong died while in the custody of the seven police officers. It noted that Pol Col Thitisan was the leader and that the cause of Chiraphong's death was asphyxiation.
"The death resulted from the officers covering the man's head with a plastic bag in an interrogation room at the police station," he said.
Mr Sompong said the other six officers named in the report are Pol Maj Rawirot Ditthong, Pol Capt Songyot Khlainak, Pol Lt Thoranin Makwanna, Pol Sen Sgt Maj Suphakon Nimchuen, Pol Sen Sgt Maj Wisut Bunkhiew and Pol Lance/Corp Pawikon Khammarew.
Pol Col Thitisan has been charged with premeditated murder by means of torture, unlawful deprivation of liberty and malfeasance.