More than 35 years after their plane crashed and burned on a Laos mountainside, the remains of nine Navy crewmen have been identified and returned to their families, Pentagon officials announced Tuesday.

They are identified as Cmdr. Delbert A. Olson, Casselton, N.D.; Lt. j.g.s Denis L. Anderson, Hope, Kan.; Arthur C. Buck, Sandusky, Ohio; and Philip P. Stevens, Twin Lake, Mich.; Petty Officers 2nd Class Richard M. Mancini, Amsterdam, N.Y.; Michael L. Roberts, Purvis, Miss.; Donald N. Thoresen and Kenneth H. Widon, Detroit, and Petty Officer 3rd Class Gale R. Siow, Huntington Park, Calif.

A group burial will be held at Arlington National Cemetery on June 18.

Members of the covert VO-67, Olson and his crew were based at Nakhon Phanom Royal Thai Air Force Base during the Vietnam War. On Jan. 11, 1968, the nine departed on board a Navy OP-2E Neptune aircraft to drop electronic sensors, which guided armed, allied planes to enemy convoys along the Ho Chi Minh Trail.

During his last radio contact, Olson said he was going to dip through a hole in the clouds to drop the sensors. Two weeks after the crew failed to return, an Air Force aircrew photographed what appeared to be the crash site, but enemy activity in the area prevented a recovery operation, according to the Pentagon’s news release.

Recovery operations took nine years, from 1993 to 2002. During that time, six U.S.-Laotian investigation teams led by Joint Task Force Full Accounting gathered aircraft debris, interviewed local villagers and surveyed the crash site, according to the Pentagon. In 1996, team members recovered identification cards of several crewmembers and human remains. The U.S. Army Central Identification Laboratory Hawaii launched full-scale recovery missions in 2001 and 2002, recovering more remains and crewmember identification materials.

More than 1,900 Americans are missing in action from the Vietnam War.

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