TOKYO—The disappearance of a young Japanese woman this month turned tragic over the weekend when police found her severed head in a suitcase.

The American man suspected of killing her, Yevgeniy Vasilievichon Bayrakta, a 26-year-old resident of New York City, originally was arrested last week on charges he’d imprisoned her. Today the Hyogo Prefecture Police announced that they had found the woman’s head and, based on the testimony of Bayrakta, they had found what appeared to be the rest of her dismembered body scattered in isolated mountain forests in Osaka and Kyoto.

The victim, a 27-year-old office worker from Sanda City in western Japan, went missing on Feb. 16.