The Am Cyanide case is one of the most chilling serial murder cases in Thai history, involving Sararat Rangsiwuthaporn, a woman accused of killing 14 people using cyanide between 2015 and 2023. The case gained national attention in April 2023 after the mysterious death of her friend Siriporn Khanwong.
Sararat, dubbed “Am Cyanide” by the media, allegedly used cyanide to poison friends and acquaintances, many of whom had either loaned her money or possessed valuables she wanted. Her crimes went undetected for years as most victims’ deaths were initially ruled natural, often taking place in remote or private settings with no immediate suspicion of foul play.
The turning point came on April 14, 2023, when Sararat and Siriporn visited a riverbank in Ratchaburi province to perform a Buddhist ritual. Siriporn suddenly collapsed and died. A police investigation revealed cyanide traces, and Sararat was arrested on April 20, 2023. She was denied bail, and further inquiries quickly expanded the scope of the case.
Following her arrest, relatives of past victims came forward, raising suspicions about other sudden deaths tied to Sararat. Investigators ultimately connected her to 14 suspected murders and one failed poisoning, in which the victim survived. Authorities stated that the murders were likely driven by a crippling online gambling addiction, and Sararat reportedly stole money, jewelry, and personal belongings from her victims.
On June 30, 2023, Thai police forwarded over 75 criminal charges to the public prosecutor. These included premeditated murder, attempted murder, theft resulting in death, and document forgery. Prosecutors officially filed the case on July 18, 2023, making it one of Thailand’s most complex serial crime prosecutions in recent memory.
Sararat’s ex-husband, Police Lt. Col. Withoon Rangsiwuthaporn, and her lawyer were also implicated for allegedly helping conceal evidence and obstructing the investigation. Withoon received a 16-month prison sentence for his role in the cover-up.
The first trial — concerning the murder of Siriporn — concluded in November 2024, with Sararat convicted and sentenced to death. The remaining trials are ongoing, with each case involving a separate victim.
Sararat remains in custody as prosecutors and investigators work through the evidence in the remaining 13 suspected murders. If proven, she would be among the most prolific female serial killers in Southeast Asian history.
