Convicted murderer Somchai Khunploem can stay at Chon Buri Hospital indefinitely for health reasons, the Corrections Department says.
The former "godfather of Chon Buri" whose son Sonthaya serves as culture minister in the current government was recently caught after years on the run.
He has been committed to jail to serve a 30-year sentence, but has spent very little time behind bars. He was transferred to the hospital on the first day of his jail term because of health concerns.
Kobkiat Kasivivat, deputy director-general of the Corrections Department, said Somchai fainted in a toilet at the hospital a few days ago and doctors have now sought to prolong his stay there indefinitely.
"The Chon Buri prison has deployed warders in front of the patient's room at the hospital.
"They are there around the clock. The department is doing its job, and extends him no favours," Mr Kobkiat said.
Amnart Prachyaphan, governor of Chon Buri prison, said doctors had written saying that returning Somchai to prison would compound his heart disease.
Somchai, better known as Kamnan Poh, was sentenced to 30 years and four months for masterminding the murder of a local administrator in 2003 and land corruption in a garbage dump project in Chon Buri in 1992. He was arrested early last month after spending more than six years on the run.