Khanakorn Pianchana pulled out a pistol and shot himself in the chest after acquitting five defendants of murder and firearms charges that could have condemned three to death.
He was rushed to hospital where he underwent surgery for injuries said not to be life-threatening.
A 25-page statement he posted on Facebook before the incident, shows that the case he was hearing concerned national security and was related to secret association, conspiracy and gun-law offences.
In the alleged document, he accused his superiors of trying to force him to change the verdicts to guilty. Khanakorn contended that the evidence did not support a guilty verdict.
Messages reading “Return the ruling to the judges” and “Return justice to the people” were repeated three times in the document.