Updated

The mission was clear. President Gerald Ford ordered a helicopter filled with 27 Marines to rescue an American cargo ship, the SS Mayaguez, that had been overpowered by the Khmer Rouge, KDVR.com reported.

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It was May 1975, less than two weeks following the fall of Saigon, and the Marine helicopter took on a hail of bullets fired from the ground and swift boats. The helicopter crashed. Of those on board, 13 were rescued and the other 14 were declared missing, including Pfc. James Jacques, who was from La Junta in southeastern Colorado and all of 18 years old at the time.

It was the last combat incident from the war and Ford had called the attack an act of piracy.

The U.S. government was able to identify all but four Marines killed in the crash, but could not positively identify Jacques.

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"We were always wondering what happened to him, Delouise Gurra, the Marine's sister, told KDVR.com. "Maybe he was a prisoner of war."

Years passed, and in 1995 there was a Cambodian man who had been carrying Jacques dog tag for a number of years, Gurra said. The man handed the dog tag over to U.S. officials. Also that year, Jacques' remains were thought to have been located underwater.

"That gave us renewed hope," she said.

With the advancements in DNA testing, the Defense Department told Jacques’ family in August that it was able to identify his remains 17 years after the discovery.

Jacques will be buried Tuesday at Fort Logan National Cemetery in Denver.

"We have been waiting for years to find out what really happened to Jim," said Gurra, who was on the tarmac at Denver International Airport on Monday for an American Airlines plane carrying his remains. "Thank God he’s home now."

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The Associated Press contributed to this report