The Phitsanulok Provincial Prison chief is facing a disciplinary probe regarding events that led to the recent deaths of four inmates.
A panel earlier set up to look into the deaths found there were reasons to believe Lt Wasant Khamnuan might have committed gross disciplinary violations as a result of his failing to address illnesses among inmates, Corrections Department chief Naras Savestanan said yesterday.
"He seemed not to effectively deal the problems or failed to hospitalise inmates when he needed to," Pol Col Naras said.
Officials are waiting for the autopsy results to confirm the cause of their deaths.
An initial investigation found they "died of the same ailment within a short time of each other" during the New Year holidays, Pol Col Naras said.
Health officials said the prisoners showed food poisoning symptoms prior to their deaths, which included numb limbs caused by low potassium levels in their blood.
It is possible the inmates consumed contaminated food additives such as those found in food seasoning that could have increased thyroid hormone levels which are harmful to the body, Pol Col Naras said.
Earlier this month, prison officials sent 24 inmates who were found to have an overactive thyroid and high heart rate to hospital.
They were among 690 inmates who fell ill and showed various symptoms including low potassium levels following physical checks-up conducted on 3,000 inmates.
The large number of sick patients was believed to be the result of a recent transfer of sick inmates from other jails to Phitsanulok Provincial Prison which is equipped with better medical facilities.
The other theory is the inmates were given food that lacked vital nutrients and that many mixed seasoning powder -- used mainly to flavour soup -- with their rice to make their food tastier.
Following the deaths, the Corrections Department is planning to ban prison shops selling food seasoning powder to inmates, according to a source close to the investigation.
The inmate deaths prompted the relative of one victim to petition the House committee on law, justice and human rights to look into the department's actions regarding this case.
"I'm ready to clarify all issues before the committee if necessary," Pol Col Naras said.