Police suspect their conditions worsened to a point where Supatra Tancharoen hallucinated and killed her mother before committing suicide to avoid punishment.

Following a homicide report, police raided a two-storey townhouse in Cholthep Village in Tambon Bang Phli Yai at 12.30am yesterday to find Supatra and her mother Chalom Tancharoen, 74, both with slashed throats. They had been dead for more than five hours.

A kitchen knife and a seven-inch (17cm) fruit-peeling knife were found near their bodies. The house - with herbs scattered everywhere and no electricity - had no signs of a struggle. The bodies were later sent for autopsies.

Supatra's 19-year-old daughter Charoenrat told police that her parents had separated a long time ago, leaving her mother to care for her grandmother, who had suffered mental illness for over a decade.

After taking care of Chalom for five years, Supatra herself suffered mental illness, prompting Charoenrat's father to take both women to Somdet Chao Phraya Psychiatric Hospital many times.

But their conditions did not improve because they did not take prescribed medicines, she said. Instead, Chalom sought herbal remedies to treat herself and Supatra.

Charoenrat said the two wrongly believed that someone was after them and each carried a knife "for self-protection".

With her father working in Bangkok and Charoenrat staying with relatives in Pathum Thani, no one paid the bills, so six months ago the house had its electricity and water cut off, she said.

Charoenrat said her mother called on Tuesday afternoon and asked her to come home. She arrived at 11pm to find the home unusually quiet and dark. After flashing a light through a window she saw the dead bodies, and then called police.

The Nation