A Samut Prakan prison inmate who suffered severe bruises and burns while being "disciplined" by officials survived the ordeal but died afterward when he choked on his food, authorities say.
The punishment was administered after drugs had been smuggled into the facility, Narat Svetananda, director-general of the Corrections Department, said on Saturday.
He said 16 to 18 inmates were questioned after the discovery and the discipline session followed.
"There are grounds that the officials might have overreacted but we have yet to determine how serious their offence is," he said.
Pol Lt Col Narat said some officials had to be temporarily moved so that prisoners would feel free to talk, referring to the transfer of the prison's chief early in the day.
"If it's concluded their action was a crime, the officials will be handed over to police," he said.
Narat: Officials "might have overreacted"
Pattanachirapong Boonyasema, 34, died on Wednesday. His wife, who has not been named, went public with allegations that he had been tortured after seeing the condition of his body at Bang Bo Hospital.
She joined Pattanachirapong's parents, Anan Boonyasema, 64, and Mali, 70, in filing a complaint with Samut Prakan police on Saturday evening. They said they believed he had been murdered.
A source on the investigation team said 10 prison officials ordered a military-like disciplinary session on Pattanachirapong.
He was beaten with batons and told to roll bare-skinned on concrete floors and sit in the sun. Water was then thrown on him. All the while his hands were tied with plastic handcuffs.
The session took all morning before he was allowed to go eat in a canteen, where he choked to death.
The officials said they wanted to extract more information on the drugs that Pattanachirapong allegedly smuggled in.
"The case [of the punishment] has grounds and the officials might have overreacted, causing the death," the source said. "However, it lacks intent as the victim did not die immediately. His subsequent choking while eating, however, was the result of the officials' action."
Pol Lt Col Narat said he would ensure justice is served and offer a remedy to the relatives. He hoped the case served as a wake-up call for all warders.
"More than 70% of the inmates are serving drug-related sentences. They are generally poor and uneducated with no jobs. They should be treated humanely. While detained, they should be educated, trained and rehabilitated.
"I'm not in an ivory tower. I understand the intention of officials who need to be strict about the smuggling of mobile phones and drugs. If their supervision is lax and the items are found, they would be transferred and face disciplinary action. But they must adjust themselves and refrain from using violence because society can't accept this."
Pattanachirapong was serving a sentence of three years and nine months for a second conviction for drug offences. At the time of his death, he had one year and eight months left to serve.