The remains of Air Force Tech. Sgt. William Kevin Colwell were recently identified at a military lab in Hawaii.
He disappeared in 1965 when his plane crashed in Laos. He was 44 at the time of his disappearance.
Relatives held a funeral mass at St. Patrick Roman Catholic Church in Glen Cove.
"When I saw the coffin, it hit home," said Colwell's niece, Ann Famigliette. "And my sister and I, it's very hard for us to see that part, very hard."
In 2010, a team of researchers recovered bits of human remains from a jungle crash site in Laos.
In March, researchers positively linked the remains to the long missing Colwell.
More than 1,660 Americans are still listed as missing from the Vietnam War, which ended in 1973.
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