A U.S. Marine in his 20s is facing criminal charges including allegedly raping a woman last month in a restroom of an American military base in Japan's Okinawa, investigative sources said Wednesday.

The Okinawa prefectural police referred the case to prosecutors on April 7, the sources said, adding the suspect is also accused of injuring another woman who tried to rescue the victim, who was a resident of Okinawa and a civilian worker at the base.

Japanese police, with cooperation from the U.S. side, launched an investigation at the base and questioned the Marine on a voluntary basis, the sources said.

The suspect was under control of U.S. authorities in line with the bilateral Status of Forces Agreement, which governs the operations of the U.S. military in Japan.

Three U.S. service members have been indicted over as many alleged sexual violence cases since June last year in Okinawa, the southern prefecture that hosts the bulk of American military facilities in the country.

Okinawa Gov. Denny Tamaki, in reaction to the latest sexual assault case, said, "It is very deplorable. We'll strongly urge the U.S. military to take measures that would be effective to prevent a similar incident."