A U.S. serviceman and a Japanese woman were found dead Saturday at an apartment in the southern island prefecture of Okinawa, local police and the U.S. forces in Japan said.

The 32-year-old U.S. Navy member assigned to the U.S. Marine Corps in Okinawa was believed to be in a relationship with the 44-year-old woman, the police said.

The police received an emergency call at around 7:25 a.m. and found the two lying on a bed at the woman’s apartment in the town of Chatan. Their deaths were confirmed later at the scene.

U.S. military sources said the man may have killed the woman and then committed suicide. They both had stab wounds.

A U.S. Marine Corps official in Okinawa told Kyodo News the man is believed to be a member of the U.S. Marine Corps’ 3rd Marine Division headquartered in the prefecture, and promised to fully support prefectural police in their investigation.

U.S. Ambassador to Japan William Hagerty expressed his deep regret over the incident during a phone call with Japan’s Vice Foreign Minister Takeo Akiba. The two agreed to cooperate in the investigation, according to the Japanese Foreign Ministry.

Okinawa hosts the bulk of U.S. military facilities in Japan. Local residents have long been frustrated with noise, accidents and crimes linked to the U.S. bases.

==Kyodo