One day in 1969, when Paul Clever was 6, he stepped off the school bus and saw a blue sedan parked in front of his family's house in Hartwell, Ga.

"I remember going in through the screen door and seeing my mother crying and two Air Force officers standing there awkwardly," he recalls.

After they left, his mother told him and his sister that their father, Tarentum native Sgt. Louis Clever, had been lost and that the Air Force was looking for him. He was 32.

"My attitude was that of a 6-year-old boy," said Mr. Clever, now 50 and living in Olive Branch, Miss., outside of Memphis, Tenn. "'If Daddy's lost, let's go find him.' And I've spent my life doing that."

The result of that search will culminate today in a public repatriation ceremony at Olive Branch High School for the remains of Louis Clever and nine of his fellow crew members.

Their EC-47Q spy plane crashed, presumably as the result of enemy fire, in southern Laos on Feb. 5, 1969, in deep jungle near the Ho Chi Minh trail.

The commingled remains of some but not all of the 10-man crew were buried together later that year at a site in Jefferson Barracks National Cemetery near St. Louis. The tombstone listed all 10, but the military's best guess was that the bones represented seven of the crew.

Another partial recovery effort in 1995 found some additional items, including a dog tag for one of the crew.

But the families of the lost men were left without a definitive accounting of what happened to their loved ones.

That finally changed in 2011, when Mr. Clever, a diagnostic engineer then working in Bangkok, started a nonprofit group called Maximum Recovery in Southeast Asia with the goal of making sure a complete effort has been made to recover all remains.

He and his wife, Nita, a Thai national, traveled last year on their own to the crash site.

Scavengers had long since removed most of the plane, but the Clevers found small pieces of it along with clothing, part of what Mr. Clever believes was his father's flight jacket and 20 bone fragments.

Spurred on by Mr. Clever's group, the Air Force in January disinterred two caskets at Jefferson that contained 30 pounds of bones from the dead crew for DNA testing at a military lab in Nebraska.

After today's ceremony, the 20 fragments found last year will also be turned over to the lab, Mr. Clever said.

The idea is to finally close a chapter in history and account for all 10 men; some family members had held out hope that a few of the crew may have parachuted out and were held captive.

"My mother never accepted that he had been killed," said Sgt. Clever's younger brother, R. Paul Clever, 74, who lives in New Kensington. "My dad and I accepted it."

Paul Clever never doubted his father had died, but he wanted to resolve a mission that began when he was 6.

"Whenever you see a news clip from the Vietnam War, you're looking for your father," he said. "It becomes a lifelong pursuit."

Louis Clever was born in Tarentum in 1936, the son of a gas company employee, and grew up with his twin sister Lois and his brother, R. Paul. The family moved to Freeport the same year Louis and Lois were born and stayed there until 1956, when they moved to New Kensington.

Louis graduated from Freeport High School in 1954 and joined the Air Force a year later. R. Paul followed suit in 1957. There weren't many jobs available at home, and the military provided a future. Both men were also patriots and believed in serving their country. R. Paul stayed in for five years but Louis became a career airman, using his skills and interest in radio communications to become a technical sergeant.

"I know he loved his work and was a consummate professional," said his son. "He was very serious. He had that type A personality, and he was pretty bold."

While stationed at Lackland Air Force Base, where he was an instructor, he met his wife Deborah, an Air Force clerk. They married in 1958 and started a family.

They were stationed in West Germany in the mid-1960s as the Vietnam War escalated. The family moved to Hartwell, Ga., Deborah's hometown, while Sgt. Clever trained at several bases in preparation for going to war. Then he headed overseas for service with the 6994th Security Squadron.

On Feb. 5, 1969, his spy plane departed Pleiku in Vietnam, bound for Laos, to gather radio intelligence along the Ho Chi Minh trail, the main supply line for the North Vietnamese. The crew was trained to intercept enemy radio signals and zero in on them to call in B-52 air strikes.

The plane never came back. A six-day search turned up nothing. It wasn't until May that the wreckage was found by a Laotian guerilla unit, according to government documents.

A U.S. recovery team collected what it could and the Air Force declared the entire crew dead, even though only one man, Sgt. Clarence McNeill, could be identified.

The war ended, time passed and the crash became another tragic piece of the Vietnam War.

Then, in March of 1995, a Joint Task Force Full Accounting team working with the Laotian government was searching for another wreck and came across the crash site. The searchers dug two test pits and removed additional bones and some artifacts, including watches, parachute release mechanisms and a dog tag belonging to Capt. Walter Burke.

The Joint Task Force put the items in storage and placed the site on its excavation list, according to a 1996 letter to Mr. Burke's family, but the dig never happened.

The dog tag remained in storage for 16 years until Mr. Clever contacted the Air Force Mortuary Affairs office. An official there found the tag in Hawaii and returned it to the Burke family last year.

The year before, while he was living in Bangkok, Mr. Clever and his wife had made their first trip to Laos to see if it would be possible to search for the wreck. They returned in December 2012 and found the site in a rocky river bed. They recovered bullet cartridges, underwear, pieces of trousers with blood on them, other small items -- and the bone fragments.

After the DNA testing of the remains, Mr. Clever said, the military's plan is to return them to each man's family to decide where they should be buried. Some may elect to place the bones back in the communal grave at Jefferson Barracks.

Mr. Clever said he will bury his father's remains there at the gravesite of his mother, who died in 2006.

On a website dedicated to Sgt. Clever, he recalled the last words his father said to him:

" 'You're the man of the house now. Take care of your mother.' He turned, walked through the gateway, and that was it."

Besides Sgt. Clever, these crew members will be honored at today's ceremony: Lt. Col. Harry Niggle, Maj. Homer Lynn, Maj. Robert Olson, Capt. Walter Burke, Master Sgt. Wilton Hatton, Tech Sgt. Hugh Sherburn, Staff Sgt. Rodney Gott, Staff Sgt. Clarence McNeill and Staff Sgt. James Dorsey Jr.

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