He was found dead from a gunshot wound to the head in the family mansion with a gun in his hand in the early hours of 6 September.
Multiple forensic investigations requested by the family's different factions resulted in conflicting outcomes, and it was not until 2010 that Noppadol was acquitted by the Court of Appeals.
Hangthong's mother Suwapee was matriarch of the Thammawattana family, who own and operate the Yingcharoen Market in the Saphan Mai area of Bangkok's Bang Khen District.
[4] On 5 September 1999, Hangthong, Noppadol and sister Malika Leelapan had met with a legal adviser to discuss the handling of the family estate.
At around 03:00 on 6 September, Hangthong's body was found in an armchair in Noppadol's bedroom, with a gunshot wound to the head and a .38 revolver in his right hand.
Noppadol also filed a complaint of ethical misconduct against Pornthip to the Medical Council of Thailand, which put her on probation for publicly commenting on the case.