Japan has summoned the United States envoy after a US marine was arrested on suspicion of robbing and murdering a woman.

US ambassador to Japan George Glass pledged “full cooperation” on Sunday. Lance-Corporal Devin Jacob Ballard is accused of killing 39-year-old Anna Yagi on the southern island of Okinawa, where thousands of US servicemen are stationed.

“The occurrence of such an extremely brutal and heinous incident is a matter of profound regret,” Japanese Prime Minister Sanae Takaichi wrote on social media. “As the Government of Japan, we have lodged a strong protest with the US side, while firmly demanding maximum cooperation with the investigation.”

Glass stated that the US “confirmed our policy of providing full cooperation with the investigation” while sharing his condolences on social media. The 20-year-old marine has denied the charges.

CCTV footage, according to local Japanese media, showed a non-Japanese man going into a hotel room with the Japanese woman in the city of Naha. Later on, the footage shows the man leaving by himself, with what appear to be the woman’s belongings, reports the AFP news agency.

“Incidents and accidents involving US military personnel cause significant anxiety to the local community and must never occur,” Japan’s Defence Minister Shinjiro Koizumi wrote on social media.

Japan hosts about 54,000 US military personnel, including 18,000 marines. The majority of these forces are based in Okinawa, a Japanese island that came under US administrative control at the end of World War II and was returned to Japan in 1972.

Since the handover, about 6,000 US military personnel have been arrested in Japan, according to the local newspaper Yomiuri Shimbun.