The Criminal Court on Tuesday sentenced Premchai Karnasuta to six months in jail for illegal possession of guns and rejected his request for suspension.
The construction tycoon was previously sentenced to two years and four months for poaching and bribery.
In the latest case, public prosecutors told the court that the president of Italian-Thai Development Plc was found on Feb 7 last year with unauthorised possession of three rifles, a musket and three rifle bullets at his residence in Huai Khwang district, Bangkok.
On May 1 last year he denied the charge but last month he confessed to it. Given the confession, the court commuted the jail term from one year to six months.
Earlier released on bail of 200,000 baht, Premchai was at the Criminal Court to hear the ruling on Tuesday.
His lawyer filed a request with the court proposing that he would enter the monkhood for 15 days, donate three million baht to charity and stay away from guns for the rest of his life in exchange for the court giving him a light punishment or suspending the sentence.
The court told him that he could do the good deeds for himself, but it could not accept the proposal because he was convicted in two other criminal cases by the Thong Pha Phum Court and the Criminal Court for Corruption and Misconduct Case Region VII.
Premchai was seeking bail with the Criminal Court.
Premchai, 64, and the three others were arrested at their unauthorised camp in the Thungyai Naresuan Wildlife Sanctuary on Feb 4 last year in possession of firearms and the carcasses of protected animals, including a rare black leopard.
Three days later authorities searched his residence in Bangkok and found numerous firearms and elephant tusks.
