Japan has demanded greater accountability from the United States after a 20-year-old US Marine was arrested in Okinawa in connection with the suspected murder and robbery of a Japanese woman.

The case has already stirred concern in Tokyo, with Prime Minister Sanae Takaichi describing the alleged crime as “extremely brutal and heinous” and calling on Washington to cooperate fully with Japanese authorities.

Police said the 39-year-old woman was found unresponsive inside a hotel room in Naha, Okinawa, early Saturday. She was pronounced dead at the scene, while investigators said the circumstances surrounding her death indicated that she may have been murdered.

Authorities arrested the Marine, who is stationed at the US Marine Corps Air Station Futenma, at about 1am Sunday. He was reportedly found walking through the city less than a day after the woman’s body was discovered.

Investigators are examining surveillance footage that allegedly captured a man with a shaved head, believed to be a foreign national, entering the hotel with the woman. Police said the man was later seen leaving with belongings believed to have belonged to the victim.

The US Marine Corps said it had offered condolences to the woman’s family and was treating the allegations seriously. The military said the Marine is assigned to the III Marine Expeditionary Force and that it is cooperating with the Japanese investigation.

The US Embassy in Tokyo also confirmed that an American service member was being held following the death of a Japanese national. It said US officials were working with Japanese authorities while investigators establish what happened.

The incident has renewed sensitivities surrounding the sizeable US military presence in Okinawa. Although the island remains strategically important to the US-Japan security alliance, the conduct of American personnel has periodically triggered anger among local residents.

Tensions reached a major point in 1995 after three US servicemen were accused of raping a 12-year-old Japanese girl, an incident that sparked widespread protests and intensified opposition to the US military presence.

Japanese authorities have now called for disciplinary measures within the US military and steps to prevent similar incidents. The investigation into the latest case remains ongoing, and the allegations against the Marine have not been proven in court.