A police officer who challenged the prime minister's order scrapping the position of official interrogator was found dead at his house on Friday, less than a week after he filed his complaint.
Pol Lt Col Jan Chaisawasdi, a senior interrogator at Thien Thalae police station, was found hanging by the neck from the backdoor of his home in Bang Bon district.
A preliminary investigation by Samae Dam police station, where the house is sited, pointed to suicide, police said.
His death was immediately reported to national police chief Gen Chakthip Chaijinda, also said he believed Pol Lt Col Jan had committed suicide and that it may be linked to the plan to eliminate the position of official police interrogator.
Forensic officials and police investigators from the Metropolitan Police Bureau were still at the scene examining and collecting evidence.
Pol Lt Col Jan was the secretary-general of the Confederation of Police Interrogators, who lodged a complaint with Gen Prayut Chan-o-cha through the government complaints centre near Government House on Monday this week.
The petition asked for a review of the order issued by the prime minister on Feb 5 as head of the National Council for Peace and Order.
The order, to take effect on Feb 20, eliminates the position of police interrogator. Official interrogators will instead be graded in normal positions at police stations with the rank of deputy inspector up to commander.
In the letter sent the prime minister on Monday, Pol Lt Col Jan said the order blocked about 2,900 police interrogators from career advancement and about 700 senior police interrogators would lose their position allowances, worth 20,800 baht per month.
However, the order said interrogators would keep their position allowances provided they continued to be responsible for interrogations.
Pol Lt-Col Jan passed his senior interrogator examinations last year and was due to be promoted to police colonel next Monday, five days before his position is to be voided.
Former Democrat Party MP Watchara Petchthong questioned the assumption of suicide, pointing out that the officer was due get a good promotion in rank next week.
Pol Lt Col Jan had told him after lodging the complaint on Monday that he was under pressure from his supervisors. He had then lost contact with him for two days, said Mr Watchara, who also opposes the NCPO order scrapping the position of police interrogator.
Mr Watchara said murder could not be ruled out at this stage.
He had sent an open letter to the prime minister shortly after Pol Lt Col Jan wa found dead, urging him to allow the Department of Special Investigation to take over the case from police, and to look into a motive behind his death.
However, Deputy Prime Minister Gen Prawit Wongsuwon said he still believed the man had committed suicide, and the reason was not related to his campaign against the NCPO's order.