A woman was arrested in Kampong Thom province late on Tuesday on suspicion of killing her elderly grandmother in Teuk Vil commune’s Prek Thmey village, in Kandal province’s Sa’ang district, earlier that day.

Phon Sophal, the crime bureau chief at Kampong Thom provincial Military Police station, said the 27-year-old suspect was arrested at 11:30pm on Tuesday in Damrei Choankhla commune in Kampong Thom province’s Stung Sen district.

He said she had hacked her grandmother, Lach Lao, 81, to death with a meat cleaver and escaped to the home of a relative in Kampong Thom, but his officials had not seen any relatives at the house.

Sophal said the suspect acted like a person who had a mental health problem. “She spoke and acted in a silly way, but we are not experts in metal health to prove that. We contacted the Kandal Military Police immediately after we arrested her,” he said.

A Military Police officer in Kandal, who asked not to be named, said his unit went to pick the woman up from Kampong Thom early on Wednesday.

The source said she was being questioned in Kandal province before being sent to the provincial court.

He said that before escaping to Kampong Thom, the suspect called her older sister, telling her that she had killed their grandmother because she was furious with her – claiming that the victim had had an affair with the suspect’s ex-husband, whom she had divorced several years ago.

“The suspect confessed that she hacked her grandmother to death so she couldn’t continue the affair with her ex-husband anymore,” the Military Police officer said.

He said that judging by her behaviour, she was suffering from mental illness and his officials would work with her family to confirm her condition after they had held the funeral.

According to a Sa’ang district police, the victim suffered injuries to her head and other parts of her body.

The National Police reported that the victim was cleaning her home when the suspect walked towards her and grabbed a cleaver from a bag.

The victim was struck several times and quickly succumbed to her injuries, the National Police said. The suspect then fled the scene and escaped the province.