I experienced a similar situation many years ago when I lived in North Thailand. A young member of the Thai family was accused of murdering a Malaysian relative. After arrest and interrogation, he confessed to the crime. During the trial, which I attended, it transpired that the confession was obtained at gunpoint. The trial was halted and the accused released. Later investigations identified two Laos "contract killers", one of whom was arrested, found guilty and imprisoned. The other "did a runner" back to Laos and is, to my knowledge, still free today.