Tiwagorn Withiton, the political and human rights activist recently hospitalised in Khon Kaen after speaking out about Wanchalearm Satsaksit's disappearance, was released on Wednesday.
A Khon Kaen Psychiatry Hospital official told the Bangkok Post that Mr Tiwagorn, 47, had spent 14 days "receiving treatment".
On July 9, Mr Tiwagorn was seized by six hospital personnel and handcuffed by a soldier from Internal Security Operations Command at his home. He was then taken to the mental hospital and sectioned.
Earlier that day, Mr Tiwagorn had posted on his social media account that officials had come his house and asked many questions about his mental health. He told them that he knew they were seeking to arrest him because of his political views but would not blame them as he understood they were just following orders.
During his 14-day detention, many rights activists appealed for his release. Since being released, Mr Tiwagorn has remained silent on social media.
Known in the past for supporting the United Front of Democracy Against Dictatorship, commonly known as the red shirts, the activist had resumed his political activities and was seen wearing anti-monarchy T-shirts after the disappearance of Mr Wanchalerm, another political advocate who faced lese majeste charges and who had taken refuge in Cambodia.
Recently, Jatupat Boonpattararaksa, the human rights defender better known as Pai Dao Din, filed a petition with the Khon Kaen Provincial Court asking for Mr Tiwagorn's released. The court dismissed the petition.