A U.S. service member was arrested on suspicion of murder and robbery after a Japanese woman’s body was discovered in a hotel in Okinawa, local officials said, describing the alleged killing as a “heinous” incident that prompted the Japanese government to lodge a protest with the United States.

Shinjiro Koizumi, the Japanese minister of defense, said a U.S. Marine lance corporal was arrested on Sunday after the woman’s body was found early on Saturday in Naha, the capital city of the Okinawa prefecture.

NHK, Japan’s public broadcaster, identified the suspect as Devin Jacob Ballard, 20, who was stationed at U.S. Marine Corps Air Station Futenma, a base a few miles outside Naha. The broadcaster identified the alleged victim as Yagi Anna, 39, saying she was pronounced dead at the scene after being found at about 4:30 a.m. on Saturday.

Japanese Prime Minister Sanae Takaichi said the Okinawa Prefectural Police were investigating the incident as a murder.