The wife of a high-level police officer has been arrested for the murder of a woman from Kanchanaburi, and investigators suspect her involvement in the deaths of six other women.

Police identified the suspect as Sararat "Aem" Rangsiwuthaporn. The husband's name was not revealed, but he was reported to be a deputy provincial police superintendent in Ratchaburi province.

Police arrested Ms Sararat on Tuesday about 11am at the government office complex on Chaeng Wattana road in Bangkok. She had a bottle of cyanide in her possession.

The arrest followed a complaint by the mother and the elder sister of Siriporn "Koy" Khanwong, 32, who was from Kanchanaburi. Ms Siriporn collapsed and died on the bank of the Mae Klong river in Ban Pong district, where she went with friends to release fish for merit-making on April 14. Cyanide was found in her body.

Investigators came to the belief that Ms Sararat might be the person who mixed cyanide in Siriporn's food, causing her death. She allegedly also stole the victim's valuables.

Police said the investigation was being expanded into whether Ms Sararat had anything to do with the deaths of six other women she had been in contact with and who died in a similar manner. Two of the seven who died were policewomen.

About 11pm on Tuesday, the death of another woman, Kanika Tuladecharak, 44, was brought to the police's attention by her father and daughter. The two believed Ms Sararat was responsible for Kanika's death.

The daughter said that on Sept 11, 2022, Kanika drove from her home in Bangkok to meet Ms Sararat in Ratchaburi. From there, her mother travelled in the same car with Ms Sararat.  According to an account given to her family, Kanika later fainted and died at a PTT petrol station. She said some of her mother's valuables had disappeared, including a mobile phone, cash and some gold jewellery.

The family suspected Ms Sararat was responsible for Kanika's death.