The woman nicknamed “Am Cyanide” by Thai media made headlines in 2023 as Thailand’s first suspected female serial killer after police uncovered evidence that more than a dozen of her close acquaintances had died in mysterious circumstances.

Evidence indicated that Sararat Rangsiwuthaporn had murdered at least 14 victims, including her former husband, between 2015 and this year, according to investigators. The motive was money, they said.

The case against Sararat, 36, has already gone to court, with her former husband, Pol Lt-Colonel Witoon Rangsiwuthaporn, and her lawyer Thannicha Aeksuwannawat accused of tampering with evidence and helping her to evade punishment.

If convicted, she could face the death penalty.

Shocking discovery

Married to Witoon until last year, Sararat was reportedly pregnant with the baby of one of her victims at the time of her arrest on April 25. Police arrested her on suspicion of poisoning a friend, Siriporn Khanwong, and stealing her valuables.

Sararat had initially not been a suspect in the sudden death as she was considered to be Siriporn’s friend.

But suspicions arose after it was found she had accompanied Siriporn on a riverside merit-making rite to release fish after initially denying being there. An autopsy found traces of cyanide in Siriporn’s body.

As investigators dug deeper, they discovered that more than 10 close acquaintances of Sararat had died suddenly after spending time with her. Among her alleged victims were her common-law husband and female police officers.

The series of alleged poisonings dated back as far as 2015. That year, a woman who had asked Sararat to manage her condo rental while she spent time overseas died on her return to Thailand after being picked up by Sararat from the airport.

While Sararat’s relationships with the alleged victims were generally good, police suspect she killed them to steal their valuables or escape debts she owed them.

But the friendly relations she enjoyed with her ill-fated acquaintances meant she never fell under suspicion. All that changed this year, when police and media publicized CCTV footage showing Sararat’s strange behavior at the scene of Siriporn’s death. While Sararat accompanied her acquaintance to the spot, she left quickly after Siriporn suddenly collapsed and strangers tried to revive her.

Not even the sole survivor of Sararat’s alleged poisoning spree suspected anything was amiss at first. Kantima Paesa-ard said she got to know Sararat as both were married to police officers. Kantima’s husband is also a former classmate of Witoon. The connections meant Kantima had been happy to lend Sararat 250,000 baht.

Last year, Kantima accepted Sararat’s invitation to eat at a shopping mall. During the encounter, Sararat handed Kantima a pill that she claimed was herbal cough medicine.

“After taking the pill, we said goodbye,” Kantima recounted. “But not long after, I felt a tightness in my chest and had difficulty breathing. I called Am, but she said she could not come to help me as she was lost. I then called the 1669 emergency hotline. I don’t know what happened next, but I was told later that CPR staff resuscitated me.”

She said she didn’t suspect Sararat at the time, instead believing she had developed a serious allergy to an ingredient in the “herbal pill”.

“But after Sararat’s alleged crimes were reported in the media, I realized she had used the same tactic with others,” Kantima said. “I too could have been one of her victims.”

Following the cyanide trail

Police said Sararat ordered cyanide that she then used to kill her victims. Because cyanide is water soluble and does not have a strong odor, it can be easily slipped into a drink without anyone noticing the difference. Cyanide interferes with the body’s ability to use oxygen and can cause death in a matter of minutes.

Because Sararat’s alleged victims had no serious conflicts with anyone, their deaths did not arouse suspicions until Siriporn’s case came to light.

“Their symptoms suggested heart failure. So, relatives had no doubts,” said deputy national police chief General Surachate Hakparn.

Police found that several of the deaths under investigation occurred just after cyanide ordered online by Sararat was delivered to her.

Cyanide has never before been used as a murder weapon by convicted serial killers in Thailand.

Authorities have tightened controls on cyanide in the wake of Sararat’s case.

By Thai PBS World’s General Desk