On April 14, 2023, Siriporn Khanwong, a 32-year-old businesswoman from Kanchanaburi province who led a rotating savings group, went with a friend to a river in Ban Pong district, Ratchaburi, west of Bangkok, to release fish as an act of Buddhist merit-making. She collapsed and died there. The friend was Sararat Rangsiwuthaporn, then 36, known by her nickname Am. Eleven days later police arrested her on a warrant for premeditated murder, and within weeks they had linked her to more than a dozen other sudden deaths among the people around her.
The inquiry that followed was one of the largest in Thai police history. In June 2023 investigators announced fifteen poisoning cases between 2015 and 2023, fourteen of them fatal, and more than 75 charges. The prosecutions have since moved through Bangkok's Criminal Court one case at a time. As of September 22, 2026, the court had ruled in eight of the fifteen cases: it convicted her of murder in five, sentencing her to death in three and to life imprisonment in two, and acquitted her in three. All of the rulings remain open to appeal, and she denies every charge. The Thai press named her "Am Cyanide".
Little is known about Sararat Rangsiwuthaporn's early life. Thai news reports describe her as the former wife of Police Lieutenant Colonel Withoon Rangsiwuthaporn, a deputy superintendent in Ratchaburi province; reports differ on his station, The Nation naming Ban Pong and the Bangkok Post and Khaosod English naming Suan Phueng. Withoon told police they had divorced over money, and The Nation reported in May 2023 that the couple had divorced about three years earlier but had gone on living together in police housing in Kanchanaburi until 2022. Investigators, the paper said, suspected the divorce had been a way to protect him.
Her sister runs a pharmacy, and police said early in the case that Sararat might have learned about chemicals from her. The sister denied supplying or using cyanide. Police said Sararat had a serious online gambling habit. In May 2023 the deputy national police chief, Police General Surachate Hakparn, said that about 78 million baht had passed through accounts linked to her, some of it through proxy accounts used to receive money from gamblers, and that on one day she had reportedly lost close to a million baht. In later rulings the court found that she had debts of several million baht linked to online gambling.
Police also said she had been diagnosed with psychiatric problems in the past, according to Agence France-Presse in April 2023, and The Nation reported in June 2023 that she reportedly had a mental disorder. Surachate took the other view in public, stressing that she was of sound mind. No reported court ruling turned on her mental state.
The people who died knew her through money. According to police, every case was linked to her through moneylending, used-car deals or rotating savings groups, the informal circles in which members pay in each month and take turns collecting the pot. Several of the dead had ties to police circles, as officers or the wives of officers, according to Krungthep Turakij.
Siriporn's family did not accept that her death was natural. Her car, a handbag and her phones were missing, according to a timeline published by the business daily Krungthep Turakij, and closed-circuit video placed Sararat with her. Sararat first denied having been there and then gave changing accounts of the belongings, the paper said. On April 18 she was charged with theft over the vehicle and released on bail.
On April 19 Siriporn's mother filed a complaint with the Central Investigation Bureau and then took the case to Surachate, because she feared the inquiry in Ratchaburi would be interfered with. The Institute of Forensic Medicine found cyanide in Siriporn's body. As the case became public, relatives of other people who had died suddenly after time with Sararat came forward, most of them from Ratchaburi, Kanchanaburi and Nakhon Pathom.
On April 25, 2023, officers of the Crime Suppression Division arrested Sararat at the Chaeng Watthana Government Complex in Bangkok. The Bangkok Post and BenarNews reported that she was carrying a bottle of cyanide. Her lawyer said she denied the charges, while acknowledging she had been the last person seen with Siriporn. The next day she was taken to the Criminal Court; she refused to answer questions or to give blood or DNA samples, according to Khaosod English, and the court approved her detention at the Central Women's Correctional Institution. The Department of Corrections confirmed that she was about four months pregnant.
Within days the police count rose. On April 26 Khaosod English printed a list of eleven deaths since 2020 in six provinces. By April 27, Surachate said, investigators were looking at at least thirteen suspicious deaths, and that day police charged her with premeditated murder, according to Agence France-Presse. By April 29 the Bangkok Post reported fourteen alleged victims. Surachate said they were people she owed money to, and he asked the public to report other cases.
Forensic teams found traces of cyanide in two of four cars seized from her, the Bangkok Post reported, one of them the car driven on the day Siriporn died. Weerachai Phutdhawong, an associate professor of chemistry at Kasetsart University who worked with the police, said she appeared to have some knowledge of chemistry and had bought an antidote to cyanide for herself. Police later said the cyanide was a brand made in Spain and brought in by one of fifteen Thai importers.
The early reports also told of one survivor. A woman married to a police officer said she had lent Sararat 250,000 baht in cash in September 2022 and that she later nearly died. Her case is the one attempted murder charge among the fifteen.
The husband of another woman on the list, Sawittree Budsrirak of Mukdahan, told reporters his wife had known Sararat through moneylending and had lent her more than 100,000 baht. Chantharat Wongkraisin's husband, whose wife had lent money and died in August 2022, told BenarNews he had never imagined that an ordinary person could do something so inhumane.
Police turned quickly to Withoon. He told investigators that Sararat had asked him to collect the car of Sutthisak Poonkwan, a man who died in Udon Thani on March 12, 2023, and that he drove it to Nakhon Pathom, where she sold it to a pawnshop. The Nation reported that he was first to be charged with embezzlement and using a false license plate. The Bangkok Post reported that he was dismissed from the force, arrested and charged, and that police asked the Nakhon Pathom Provincial Court to hold him on charges of receiving stolen property and of jointly forging and using forged official documents. The court released him on bail of 100,000 baht with an electronic monitor, saying police had found no evidence linking him to the deaths. After his release Surachate arranged for him to visit her in prison; Withoon had said he wanted to persuade her to confess if she was guilty.
Accounts of Sutthisak's relationship with Sararat differ. The Bangkok Post called him her boyfriend, The Nation said she was believed to have had an affair with him, and Khaosod English described him at different times as her husband and her former husband. Police said in May 2023 that they had ruled him out as a source of the cyanide.
On May 18, 2023, Surachate said that a gambling addiction may have been a factor. Investigators had traced large sums sent by people on the list to her accounts before their deaths. Families of most of the dead, The Nation reported, said money or jewelry had gone missing, in amounts from 60,000 to 300,000 baht. Agence France-Presse, as reported by CBS News, said police alleged she had taken more than $140,000 from victims.
Investigators said she favored weekends and gave relatives or associates false evidence afterward to divert suspicion. These are police descriptions, and each depends on a court finding in the individual case.
On June 30, 2023, Surachate, the officers on the case and Weerachai presented the completed investigation. Teams from the Central Investigation Bureau, the Crime Suppression Division, Provincial Police Region 7 and the Office of Police Forensic Science had interviewed more than 900 witnesses and assembled about 26,500 pages of documents over three months. The file listed fifteen cases in eight provinces from 2015 to 2023, fourteen deaths and one survivor, and more than 75 charges, including premeditated murder, attempted murder, robbery causing death, adulterating food, medicine or consumer goods causing death, and forgery. A deputy commander, Police Lieutenant General Anek Taosuparb, said she was charged with premeditated murder in all fourteen death cases, an offense that carries the death penalty.
Surachate called it a historic case. "Even Jack the Ripper from the UK did not kill this many," he said, according to CBS News. He said Sararat had planned the deaths over eight years so that they would look like heart attacks and draw no suspicion from families. He cited the case of Somkid Pumpuang, a man who killed again after release on bail, to explain why police would not let her go. Police said she denied murder, and Reuters, as cited by CBS News, reported police as saying she had admitted using cyanide. She was refused bail.
Police also addressed the rule that bars execution of a pregnant woman. In the week before the file was closed, the Department of Corrections said, a prison clinic had found no fetal heartbeat and she had been taken to the Police General Hospital in Bangkok, where the pregnancy was ended; she was then sent to the Corrections Hospital for observation. Police denied that their questioning had played a part. They said that the protection for pregnant women no longer applied.
The police chronology published by Khaosod English in July 2023, with details from The Nation and Krungthep Turakij, listed the cases in this order. They are allegations as filed, not court findings.
Monthathip Khao-in died on July 7, 2015, in Bangkok, after returning from abroad. Nittaya Kaewbuppha, 36, an engineer, died in Nakhon Pathom on August 22 or 23, 2020. Sawittree Budsrirak, reported as 40 or 41, died in Mukdahan on November 25, 2020. Darinee Thepthawee, known as Fah, 34, died at her home in Sam Phran district, Nakhon Pathom, on December 13, 2020. Surat, 35, whose surname is romanized in several ways, died at home in Tha Maka district, Kanchanaburi, on January 6, 2021.
In 2022 the file lists Police Captain Kanda Torai, 36, in Nakhon Pathom in August; Rosjarin Nilnoi, a vegetable seller, in Samut Sakhon on August 10; Chantharat Wongkraisin in Phetchaburi on August 15; Maneerat Pojanat, a teacher, in Nakhon Pathom on September 10; Kanika Tuladecharak, 44, in Ratchaburi on September 12; a woman who survived, in Kanchanaburi in September; and Pusadee Samboonmee, also a teacher, in Nakhon Pathom on November 20.
In 2023 come Sutthisak Poonkwan, 35, in Udon Thani on March 12; Police Lieutenant Colonel Nipa Saenchan, 38, in Nakhon Pathom on April 1; and Siriporn Khanwong on April 14. Reports give the ranks of the two police officers differently from one another, and the court's later list of verdicts uses some names that do not appear in the 2023 police list in the same form.
The case alarmed the public about how easily cyanide could be bought. Local media reported that she may have obtained it online. Thailand does not produce cyanide; the Department of Industrial Works told The Nation in May 2023 that fourteen companies imported it and that the department controlled the import and distribution of sodium and potassium cyanide, which are used in laboratories and mining. Its director general, Julapong Thaweesri, said the department was fast-tracking a rule requiring buyers to tell sellers what the chemical was for, and urged people not to sell it online. In June 2023 Surachate said, according to Reuters as cited by CBS News, that the government would tighten access.
Prosecutors filed charges over Siriporn's death in July 2023. Withoon and Sararat's lawyer, Thannicha Aeksuwannawat, were charged alongside her with concealing evidence and helping her evade punishment. All three pleaded not guilty. The trial ran from July 4 to September 12, 2024.
On November 20, 2024, the Criminal Court on Ratchadaphisek Road read its judgment over three hours. It found that Sararat had poisoned Siriporn with potassium cyanide on April 14, 2023, and had taken property worth 154,630 baht, and it sentenced her to death for premeditated murder. Withoon, then 40, received one year and four months in prison, a term reduced because his testimony had helped the court, and Krungthep Turakij reported that he was ordered to pay compensation. Thannicha received two years without suspension. Both were granted bail of 100,000 baht each.
Sararat showed no emotion, Khaosod English reported. Siriporn's mother wept and said that justice had been served and that her daughter could rest in peace. A lawyer for the family, Decha Kittiwithayanan, said the ruling had drawn on evidence from the related cases and could guide the trials to come.
The second judgment came on February 20, 2026. Police Lieutenant Colonel Nipa Saenchan, known as Inspector Pu, died on April 1, 2023, in Phra Pathom Chedi subdistrict, Nakhon Pathom. Prosecutors said Sararat had planned the killing to hide her own fraud against the victim. Sararat told the court she had been in Hua Hin that day; phone records and the owner of the restaurant where the two women ate placed her with Nipa, and the court found that the victim had cyanide in her body and that Sararat had ordered the chemical. The court ruled the killing premeditated and imposed death, then reduced it to life imprisonment because her testimony had been of use, according to Thairath and Thai PBS World. It found the motive was to clear online gambling debts.
One of Nipa's sisters said she was heartbroken that her sister had trusted someone close who then killed her, and that life imprisonment was too lenient. Another said the family wanted no compensation, only justice, and thanked the police and the witnesses.
On March 11, 2026, the court acquitted Sararat of the murder of Nittaya Kaewbuppha, 36, an engineer who died in Nakhon Pathom on August 22 or 23, 2020. Witnesses placed Sararat at the hospital construction site where Nittaya worked, which she had denied visiting, and a Siriraj Hospital toxicologist told the court that the autopsy findings and photographs resembled cyanide poisoning, although no cyanide test had been done at the time. The court accepted that cyanide caused the death.
What failed was the link to Sararat. The evidence of her buying cyanide dated from August 9, 2022, two years after Nittaya died, and the prosecution did not show that she held cyanide in 2020. Nittaya had pawned two cars to Sararat for 150,000 baht, and the court found that ordinary transaction gave reasonable doubt about the alleged property motive. It said it could not use the judgments in other cases against her in this one. It gave her the benefit of the doubt, dismissed three claims for compensation, and ordered her held pending any appeal, since the charge carries the death penalty.
Her lawyer said afterward that the remaining cases would divide into those before and those after August 9, 2022, the date of the cyanide order, with each turning on its own file.
On April 30, 2026, the court ruled in the fourth case, the death of Police Captain Sukanda Wimolman, known as Nui, a former deputy finance inspector at the Phu Pha Man police station in Khon Kaen province. The two women were friends. On August 9, 2022, the court accepted, they visited a hermitage together to have Sukanda's fortune read about her career and love life, ate together in Nakhon Pathom and parted; on the way home Sukanda's car left the road in Kanchanaburi province, and rescue workers found her unconscious. She died afterward. Medical witnesses for the prosecution said she died of respiratory failure caused by cyanide poisoning.
Sararat denied the charge and said she had been elsewhere. Prosecution witnesses testified that she had ordered cyanide, was the only person found with it and was the last person with the victim, and the court found their evidence credible. It imposed death, reduced it by one third to life imprisonment because her testimony had been of use, and ordered the term to run after the two sentences already imposed, according to Thairath. Reports give Sukanda's rank and the spelling of her surname in several forms.
On July 21, 2026, in the fifth case, the court acquitted Sararat of the murder of Rosjarin Nilnoi, known as Noi, a vegetable seller who died in hospital in 2022 after falling ill in Samut Sakhon. Her husband had brought the complaint after the other deaths came to light in 2023. The treating doctor found highly acidic blood, which could come from a severe infection or from poisoning, but could not confirm cyanide or say how any toxin entered the body. The prosecution's main eyewitness, an employee of the victim, could not describe the make of Sararat's car under cross-examination, and the court gave the testimony no weight.
Prosecutors had said Sararat wanted to wipe out a debt of 60,000 baht. The court found instead that Rosjarin had pawned her car to Sararat for 100,000 baht and repaid half; after the death Sararat demanded 600,000 baht from the husband to release the car, settled for 300,000 baht and returned it. The court did not find that a credible motive for murder, and found no evidence tying her to the death.
The sixth judgment, on August 4, 2026, concerned the oldest death in the file. Monthathip Khao-in, known as Sai, a wealthy friend who lived in Canada and owned rental buildings in Sam Phran district that she had entrusted to Sararat, flew home on July 7, 2015. Sararat and other friends met her at Suvarnabhumi Airport, stopped to eat, and took her to her condominium in Bangkok, where she died later that day. The court accepted that the two were close, that they belonged to the same savings group, and that Sararat had borrowed money from her; it also accepted that Sararat had a gambling problem and had lost more than 30 million baht.
The doctor who examined Monthathip attributed her death to heart failure or a possible existing illness and could not confirm cyanide. No witness clearly testified that Sararat had poisoned her. The court found several reasonable doubts and dismissed the case, according to The Standard. That made three acquittals against one death sentence and two life sentences.
The seventh judgment, on August 25, 2026, returned to a death sentence. Darinee Thepthawee, known as Fah, 34, had known Sararat since 2014 and belonged to the same rotating savings group. Sararat owed her 60,000 baht, and had also drawn her into three savings circles that would have paid out about 200,000 baht, which Darinee did not live to collect, according to MGR Online. On December 12, 2020, Sararat messaged her about going to the market in Sam Phran the next morning. Darinee was with Sararat shortly before she fell ill on December 13; she collapsed at home and was pronounced dead at Samphran Hospital.
A forensic medicine and toxicology specialist at Siriraj Hospital who performed the post-mortem testified that she died of cyanide poisoning. The court found the prosecution had proved its case beyond reasonable doubt and that Sararat, deeply in debt and unable to repay, had killed Darinee to obtain or keep the benefit of her fraud. It convicted her of premeditated murder under Sections 289(4) and 289(7) of the Criminal Code and of adulterating consumable goods causing death under Section 238 with Section 236, applied the heaviest penalty for the single act under Section 90, and sentenced her to death. Darinee's relatives embraced and wept after the sentence was read.
The eighth judgment came on September 22, 2026, in courtroom 712 under case number 856/2025. Chantharat Wongkraisin, known as Jum, 43, of Phetchaburi, had put 70,000 baht into a joint moneylending investment with Sararat and separately lent her 26,800 baht. The court found that Sararat ordered a jar of cyanide on August 9, 2022. She proposed to meet Chantharat on August 12 to repay the investment with interest, then put the meeting off after learning that Chantharat's husband and child would be home for the public holiday, and met her instead on August 15 at a gas station near her home, which the court read as an effort to avoid witnesses. After Chantharat returned home her husband found her unconscious and took her to Cha-am Hospital, where she died.
No one saw the meeting or the poisoning. The court relied on circumstantial evidence: messages arranging the meeting, transfer records and a recording of the two discussing repayment, together with a forensic specialist's evidence that her condition pointed to heavy cyanide exposure, and it noted the similarity with other cases in the file in which people fell ill after meeting her. It found her unsupported testimony insufficient, sentenced her to death for premeditated murder and adulterating consumable goods causing death, and ordered her to pay Chantharat's husband 60,000 baht with 5 percent annual interest from the date of death.
Her lawyer, Chaiya Khum-am, said she would appeal. He told reporters that bank statements and her phone had been handed to investigators but not put before the court, that a single jar of cyanide bearing none of her fingerprints had been used as evidence across all fifteen cases, and that the sum involved was small beside her transactions: he said more than 60 million baht had passed through her accounts and she had repaid 30 million. He said she had denied wrongdoing from the outset and could not be expected to show remorse.
As of September 22, 2026, Bangkok's Criminal Court had decided eight of the fifteen cases prosecutors filed: three death sentences, for the murders of Siriporn Khanwong, Darinee Thepthawee and Chantharat Wongkraisin; two death sentences reduced to life imprisonment, for the murders of Nipa Saenchan and Sukanda Wimolman; and three acquittals, in the cases of Nittaya Kaewbuppha, Rosjarin Nilnoi and Monthathip Khao-in. All of the judgments are open to appeal, and no appellate ruling had been reported. In the acquittals she remained in custody pending any appeal. She is held at the Central Women's Correctional Institution in Bangkok.
The next judgment was set for November 25, 2026, in the attempted murder case of the woman who survived. In every case not yet decided, Sararat is accused, not convicted, and she has maintained her innocence throughout.
Withoon and Thannicha were convicted at first instance in November 2024 of offenses connected with concealing evidence and helping her evade punishment. No appeal ruling in their cases has been reported.
The scale of the case is a police count, not a court finding. Police said fifteen cases, fourteen deaths and one survivor; the courts have so far found five murders proved and three not proved. Reports gave the number of provinces as seven or eight, and early counts of the dead rose from ten to fourteen within a week of the arrest.
Her mental state was described differently by different officials: as previously diagnosed with psychiatric problems, according to police quoted by Agence France-Presse; as reportedly suffering a mental disorder, in The Nation; and as of sound mind, according to Surachate.
The money figures conflict. Police said about 78 million baht passed through linked accounts; her lawyer said more than 60 million baht passed through her accounts and that she had repaid 30 million. The court in the Monthathip case accepted gambling losses of more than 30 million baht.
The source of the cyanide was disputed early. Police raised the possibility that she learned about chemicals from her sister, a pharmacy owner, and local media reported she might have bought it online; the sister denied any role. The courts in the convictions accepted that Sararat had ordered cyanide in August 2022, while the court in the Nittaya case found no proof that she held cyanide in 2020. The defense says no fingerprints of hers were found on the jar.
Sutthisak Poonkwan's relationship to her is reported as boyfriend, lover, husband and former husband. Dates of some deaths differ by a day between sources, and the ranks and names of the police officers in the file are given in several forms.
July 7, 2015: Monthathip Khao-in dies in Bangkok (first case in the police file; acquittal August 4, 2026).
August 22 or 23, 2020: Nittaya Kaewbuppha dies in Nakhon Pathom (acquittal March 11, 2026).
December 13, 2020: Darinee Thepthawee dies in Nakhon Pathom (death sentence August 25, 2026).
August 9, 2022: Sararat orders a jar of cyanide, the court finds; Sukanda Wimolman dies after a day with her (life sentence April 30, 2026).
August 2022: Rosjarin Nilnoi dies in Samut Sakhon (acquittal July 21, 2026).
August 15, 2022: Chantharat Wongkraisin dies in Phetchaburi (death sentence September 22, 2026).
September 2022: a woman survives (attempted murder case; judgment set for November 25, 2026).
March 12, 2023: Sutthisak Poonkwan dies in Udon Thani.
April 1, 2023: Nipa Saenchan dies in Nakhon Pathom (life sentence February 20, 2026).
April 14, 2023: Siriporn Khanwong dies in Ban Pong district, Ratchaburi.
April 18, 2023: Sararat charged with theft over Siriporn's car and bailed.
April 19 and 24, 2023: Siriporn's mother complains to the Central Investigation Bureau and to Surachate Hakparn.
April 25, 2023: Sararat arrested in Bangkok on a murder warrant.
April 27 to 29, 2023: police count of suspected victims rises to thirteen, then fourteen.
May 3, 2023: The Nation reports that Withoon is to be charged; the Bangkok Post later reports him dismissed, charged and bailed.
May 6, 2023: the Department of Industrial Works says it is fast-tracking new cyanide rules.
June 2023: pregnancy ends in custody.
June 30, 2023: police close the inquiry: fifteen cases, more than 75 charges.
July 2023: charges filed over Siriporn's death against Sararat, Withoon and Thannicha.
July 4 to September 12, 2024: first trial.
November 20, 2024: death sentence for Siriporn's murder; Withoon and Thannicha sentenced to prison terms.
February 20, 2026: Nipa Saenchan case, death reduced to life.
March 11, 2026: Nittaya Kaewbuppha case, acquittal.
April 30, 2026: Sukanda Wimolman case, death reduced to life.
July 21, 2026: Rosjarin Nilnoi case, acquittal.
August 4, 2026: Monthathip Khao-in case, acquittal.
August 25, 2026: Darinee Thepthawee case, death sentence.
September 22, 2026: Chantharat Wongkraisin case, death sentence (third).
November 25, 2026: judgment scheduled in the attempted murder case.