A 20-year-old US Marine stationed in Japan’s Okinawa prefecture was arrested on Sunday on suspicion of robbing and murdering a local woman.Davin Ballard, stationed at the US Marine Corps Air Station Futenma, is suspected of killing 39-year-old Anna Yagi and taking her wallet and backpack at a hotel in Naha in the early hours of Saturday, according to Okinawa prefectural police.Police said Ballard was seen entering the hotel with Yagi, who was found dead there on Saturday morning. The Marine has denied the allegations.Ballard was later spotted walking alone in Naha’s entertainment district on Saturday night, where a police officer questioned and detained him, according to police.The alleged involvement of a US serviceman prompted Japan’s foreign ministry to lodge a protest with US ambassador to Japan, George Glass, on Sunday.Vice foreign minister Takehiro Funakoshi raised the case with Glass, who told him that the US side would fully cooperate with the investigation and take all possible measures to prevent a recurrence, the ministry said.Glass separately said on X that he had spoken to Okinawa governor Genta Koja, offering condolences and pledging full US cooperation as the investigation continued.Japanese police said they would investigate the case in cooperation with the US military.Serious offences including murder, rape and robbery have previously fuelled tensions between local communities and the large US military presence in the Okinawa prefecture.Local police have stated that they have handled more than 100 criminal cases involving US service members and related personnel in 2025.