A woman in her 30s committed suicide shortly after being questioned over her possible involvement in a murder two days earlier in Imabari, Ehime Prefecture, police said Friday.

The woman was found dead in a building in Imabari on Friday morning when investigators arrived to take her in for more questioning. A suicide note was found, but the police have not released its contents or any details about how she killed herself.

The woman had been undergoing questioning on a voluntary basis since Thursday over the murder of 92-year-old Yukie Okamoto in a public housing unit in the city. In the attack, Okamoto's son, 70-year-old Hisayuki, was severely wounded.

The son has told investigators he was stabbed by a female stranger. Investigative sources said a security camera recorded footage of the woman, who lives in the neighborhood, near the scene of the crime around the time of the attack.

Police have searched an apartment connected to the woman and also seized her bicycle.

Okamoto's residence is in an area of factories and homes about 1.5 km north of Imabari Station.

On April 25, at her residence about 400 meters away, 81-year-old Satsuki Ochi was found dead with a stab wound to her abdomen.

No suspect has been arrested in that case.