Pol Capt Nattapong Wongwan, deputy inspector of Tha Hin police station, said Jirachai Paosilpchai, 75, was killed by a bullet to his chest.
Nattapong said that when he arrived at the scene with a doctor and officials from Ruamkatanyu Foundation, Jirachai has been dead for about half an hour.
His wife, Saengchan Paosilpchai, 72, told police that she did not notice any signs of her husband being suicidal and did not know when he acquired the pistol.
She said her has husband had become partially paralysed following a stroke. She said she was talking to the husband and left him just for a moment to do something. She heard a shot and ran back only to find that he had shot himself.