Then-Marine Corps Pfc. Michael Hofmaster, left, a combat engineer with the 9th Engineer Support Battalion, works on a bridge alongside U.S. and South Korean marines at Camp Josa-ri, South Korea, in August 2023. (Federico Marquez/U.S. Marine Corps)

CAMP FOSTER, Okinawa — Japanese prosecutors last week charged a U.S. Marine on Okinawa with sexually assaulting and injuring a woman this summer, the third such case on the island since December.

Lance Cpl. Michael Hofmaster, 20, was charged Friday by the Naha District Public Prosecutors Office in connection with a June 21 incident in Nago city, according to the indictment.

Prosecutors allege Hofmaster grabbed the woman by the shoulders, pushed her onto a bed and sexually assaulted her, according to the indictment. He also “caused lacerations in her vagina that required a month to heal, including seven days of hospitalization.”

Hofmaster is with the 9th Engineer Support Battalion, 3rd Marine Logistics Group at Camp Hansen, III Marine Expeditionary Force spokesman 1st Lt. Owen Hitchcock said by email Monday. Hofmaster is in Japanese custody, he said.

The Marine Corps is “cooperating with all appropriate local authorities throughout the process,” Hitchcock wrote.

“The alleged behavior does not reflect the core values of the U.S. Military,” he said. “The U.S. Military goes to great lengths to instill these values in every Marine through regular education and training throughout their service.”

Okinawa Prefectural Police forwarded Hofmaster’s case to the prosecutor’s office on Sept. 5, a spokesman for the office said that day. Hofmaster at the time was confined to military installations in Japan, according to III MEF.

The woman is older than 20 and was an acquaintance of Hofmaster, a spokesman for the police investigation team said Sept. 5. Medical personnel who treated the woman reported it to police, the spokesman said.

Some Japanese government officials are required to speak to the media only on condition of anonymity.

This case follows indictments of two U.S. service members by Japanese prosecutors on separate charges of sexual assault and attempted sexual assault that came to light over the summer and roiled Okinawa.

Senior Airman Brennon R.E. Washington pleaded not guilty July 12 in Naha District Court to charges of kidnapping and sexually assaulting a minor in December. Marine Lance Cpl. Jamel Clayton was charged in May with attempting to sexually assault a woman in Yomitan.

Those cases led to formal complaints from the prefecture to the U.S. Embassy, U.S. military and the Japanese government and calls for changes to the status of forces agreement governing the U.S. military population in Japan.

U.S. Forces Japan commander Lt. Gen. Ricky Rupp announced in July a “new forum of cooperation” with the Japanese and Okinawan governments and community members.

The Marine Corps has increased courtesy patrols in Okinawa’s popular nightlife spots and instituted near-100% outbound sobriety checks at all its Japan installations on weekends in response to the incidents.

Rupp, U.S. Ambassador to Japan Rahm Emanuel and III MEF commander Lt. Gen. Roger Turner have called for consistent liberty policies for all U.S. troops in Japan. But so far, no changes have been announced.