An American pilot whose remains were lost for decades after his B-25 bomber crashed into a mountain in Papua New Guinea during World War II is finally set to be buried this week at Arlington National Cemetery.

Maj. Donn C. Young, who died on Jan. 18, 1943, will be laid to rest with full military honors Tuesday in front of about 20 of his family members in a ceremony that will include an Air Force flyover, according to Stars and Stripes.

Young’s remains were discovered in 1998 by Alfred Hagen, a Philadelphia business owner whose great-uncle, Maj. Bill Benn, was flying with him in the cockpit on that fateful day. After advances in DNA technology, they were positively identified as his last year.

The exact circumstances surrounding Young’s death are unclear.

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Hagen told Stars and Stripes that Young and his great-uncle were flying around the Owen Stanley Mountain Range – which has peaks as high as 13,000 feet – the day their B-25, dubbed Algernon IV, went down.

“Maybe they got battle damage,” Hagen said. “They lost their left engine. There were violent thunderstorms that afternoon. The mountains were uncharted at that time, and they were trying to find a pass where they could sneak through.”

Hagen says the plane and its seven-man crew crashed while on a mission to search for locations in the jungle that Allied aircraft could land if their planes ever took on damage from Japanese forces.

A local resident discovered the B-25’s crash site in 1956 and remains taken from it the following year were buried in a mass grave in Kentucky, Stars and Stripes reports.

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Hagen then visited Papua New Guinea numerous times in the 1990s to search for the crash site himself. He finally discovered it in 1998 and brought newly uncovered remains – along with Young’s dog tags that he found there – to the U.S. Embassy in Port Moresby, the website says.

Young’s grandson, Donn Alexander, told Stars and Stripes that he submitted a DNA sample to the Defense Department in 2005 after being told they were trying to identify the remains, but “didn’t hear anything for years.”

Then last year, he says he was informed that one set of remains Hagen found were confirmed to be Young’s — a piece of news that would leave him “very happy,” as “there would be some closure on that.”

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Hagen is expected to be alongside Alexander at the funeral Tuesday.

“There is a special pain when you don’t know or don’t understand the fate of a loved one,” he told Stars and Stripes. “It was a pain that my own family knew all too well.”