A 54-year-old woman has been arrested for allegedly locking her naked partner out on their balcony for the night in an incident three years ago, which led to the man's death from extreme cold, police said Friday.

The woman was arrested on charges of assault and lethal confinement, the Nagasaki Prefectural Police said.

One day in February 2022, the woman "ordered the victim to get out on a balcony while he was naked, and confined him there," local official Masafumi Tanigawa said.

The next day, police rushed to the scene after an emergency call, and the 49-year-old man — the woman's common-law spouse — was found "nearly dead" in a room, Tanigawa said, adding the man later died of hypothermia.

The temperature that night had fallen to a low of 3.7 degrees Celsius, the Mainichi daily reported.

Prior to the incident, the woman had previously attacked her partner with a knife, which left him with nose injuries that took two weeks to heal.

The woman is denying the charges, telling police that "I've done nothing," Tanigawa quoted her as saying.

Police did not say why it took so long to formally bring charges against her.