Thailand’s Worst Serial Killer Gets Second Death Sentence in Poisoning Case Linked to Online Gambling

Thailand’s criminal court has handed a second death sentence to a woman accused of murdering 14 people with cyanide and attempting to murder another.

Sararat Rangsiwuthaporn, known colloquially as “Am Cyanide,” is thought to be the country’s worst serial killer. According to prosecutors, she is a gambling addict who killed for financial gain.

Investigators discovered Sararat had spent 78 million baht (US$2.3 million) over three years on illegal online gambling site Fun88, sometimes wagering as much as 10 million baht (US$290K) in a single day.

Sararat financed her addiction by borrowing money from her victims before killing them and stealing their valuables, prosecutors claim.

Food Laced with Poison

She was initially sentenced to death in September 2024 for the murder of her friend, Siriporn Kanwong. On Tuesday (August 25), she received a second death sentence for killing Darinee “Fah” Thepthawee, a friend and creditor.

Sararat had borrowed 60,000 baht (US$1,850) from Darinee and also persuaded her to participate in three informal savings schemes that promised returns totaling around 200,000 baht (US$6,150), according to court documents.

In December 2020, Sararat lured Darinee to a local market for food that prosecutors said she had laced with potassium cyanide.

After returning home, Darinee told her husband she felt sick. She then suffered convulsions and muscle rigidity and began foaming at the mouth before losing consciousness. She died from multiple organ failure, according to court documents.

Tuesday’s ruling was the seventh judgment in 15 cases brought against Sararat, the wife of a high-ranking police officer who moved in affluent circles. So far, she has received two death sentences, two life sentences, and three acquittals.

Sararat Arrest

Sararat was arrested in Bangkok on April 25, 2023, after the family of her last victim, Siriporn, raised suspicions about her sudden death.

Siriporn, 32, collapsed and died on the banks of the Mae Klong River in Ratchaburi on April 14 after going with Sararat to release fish as part of a Buddhist merit-making ritual.

Forensic tests subsequently detected cyanide in Siriporn’s body, and investigators came to believe Sararat had poisoned her before stealing her belongings. On her arrest, she was found to have a bottle of cyanide in her possession, police said.

Police began examining other people who had died suddenly after spending time with Sararat. Investigators discovered that many had financial connections to her through loans, car deals, or informal savings schemes, while relatives of other suspected victims began coming forward with accounts of similarly unexplained deaths.

Among her alleged victims are an ex-boyfriend and three female police officers.