NAHA, Okinawa — The investigation of possible crimes relating to the death of a Japan Air Self-Defense Force sergeant dealing in surplus U.S. military weapons has been transferred to the Naha District Prosecutor’s Office.

As a result, the investigation into the Aug. 31 accidental explosion that killed Senior Master Sgt. Takio Tamura, 53, will remain open, officials said.

Tamura was killed at an Okinawa City junkyard while cleaning decades-old, rocket-propelled grenades for resale, police said.

A police spokesman said Thursday that sending the case to prosecutors on Wednesday is “due procedure.”

“Although the suspect is deceased, the incident did occur,” he said. “It is up to the prosecutor to decide if further action needs to be taken.”

The spokesman said the transfer of the investigation was not conducted just to keep the case open.

“We are still investigating the source of the weapons, but that is separate from the charges against Tamura,” he said.

Police confirmed Thursday that the number of investigators assigned to the case has been reduced from 64 to 13.

During an initial investigation, police learned Tamura had for years collected surplus weapons, ammunition, clothing and other military paraphernalia at an illegal flea market along a public access road in an unused section of the Kadena Ammunition Storage Area, part of Kadena Air Base.

Police uncovered large caches of military gear and weapons in two houses Tamura rented in Naha, near the Self-Defense Force base where he was assigned as a mechanic.

On Sept. 6, neighborhoods surrounding the homes were evacuated while a bomb squad disabled rocket-propelled grenades believed to have been the type used by U.S. troops in Vietnam in the early 1970s.

Police had previously confiscated 26 practice grenades from Tamura’s van at the junkyard. They also recovered artillery shells, M-16 rifles, a grenade launcher, rocket-propelled grenades, gun parts and hundreds of rounds of ammunition from his Gushi district home in Naha and an apartment used for storage in the city’s Oroku district.

Police arrested two men Sept. 22 after searching the homes and businesses of people allegedly associated with Tamura.

The two were arrested for violating the firearms control law, police said. Both own military surplus shops in Okinawa City and Yonabaru.

They allegedly possessed illegal bayonets, police said. Their cases are pending.

In all, 36 homes and businesses were searched and 20 people questioned about the sale of military surplus items.

The source of the items found in the homes Tamura rented has not been determined, the police spokesman said, adding: “It is highly possible that the suspect obtained the weapons on Okinawa.”

— Chiyomi Sumida contributed to this report.

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