A court sentenced a former US base worker to life in prison on Friday for the April 2016 rape and murder of a 20-year-old woman in Okinawa.
Kenneth Franklin Shinzato was found guilty of assaulting and killing a 20-year-old local woman last year.
He admitted to charges of rape resulting in death and abandoning her body, but denied he had meant to murder her.
District Judge Toshihiro Shibata, in finding Shinzato guilty of murder, said yesterday: "The immeasurable viciousness of the accused led to the senseless killing of a young woman, who only just came of age".
Okinawa is home to the largest Marine base outside the U.S. Shinzato worked at Kadena Base, where more than 20,000 U.S. service members and their families, as well as Japanese civilians live and work.
The case has intensified longstanding local opposition to the American military presence on the strategic island, which reluctantly hosts almost 75 percent of land allotted for USA bases in Japan even though it accounts for just a fraction of the country's total area.
A spate of crimes committed by USA servicemen against local citizens has worsened the tension.
BBC noted that in 1995, a 12-year-old girl was raped by three USA service personnel.
Half of about 50,000 American troops stationed in Japan are on Okinawa.
The Okinawa parliament adopted a resolution and a letter addressed to Prime Minister Shinzo Abe and US Ambassador to Japan William Hagerty with the demand to withdraw US Marine Corps from Okinawa in light of a deadly auto accident caused by a drunken US marine.
Roughly half of the 50,000 USA troops stationed in Japan are in Okinawa.
Last month, United States marine Nicholas James-McLean, 21, was arrested after his truck collided with a vehicle driven by 61-year-old Hidemasa Taira.
The U.S. military says the crime rate among its ranks in Japan is lower than among the general public.