The military has placed a Marine sergeant in the Pearl Harbor Brig while it investigates the death of an Oregon woman in May.

The Marines and city prosecutor’s office said today the military would take over the investigation of Master Sgt. Nathaniel L. Cosby, 38, who was arrested in the death of Ivanice “Ivy” Harris, whose body was found near Yoko­hama Bay after being missing for four days.

Dr. William Goodhue Jr. of the Honolulu Medical Examiner’s Office ruled Harris’s death as a homicide, the office said today. He also found the presence of marijuana in her system.

The Medical Examiner’s Office said the cause of death  was injury to the neck.

Cosby has been administratively transferred to U.S. Marine Corps Forces, Pacific at Camp Smith, according to a joint statement from city Prosector Keith Kaneshiro and Marines at Camp Smith. Cosby is being detained in pretrial confinement at the Joint Brig Miramar – Detachment Pearl Harbor Brig on Ford Island during the criminal investigation.

No charges have been filed.

Cosby, of Jefferson, Ala., is an explosive ordnance disposal specialist who was in Hawaii on temporary duty. Navy officials said he was assigned to Joint Prisoners of War, Missing in Action Accounting Command at Hickam. Cosby enlisted in the Marine Corps in 1998.

He was stationed at Iwa­kuni Marine Corps Air Station in Japan, where he is assigned to Marine Wing Support Squadron-171, which is a part of the 1st Marine Aircraft Wing.

Harris worked as an escort. She grew up in Portland, Ore. and was living in Las Vegas, was vacationing in Hawaii with her boyfriend and a friend to celebrate her 29th birthday.