LEBANON, Tenn. — Growing up in a small Tennessee town, Lane Martin looked every day at the photo of his uncle hanging in the kitchen but knew only a few things about him: He had left Harvard Law School at the start of World War II to join the Marine Corps; he was killed in 1943 storming a Pacific atoll called Tarawa; and his body came home in a gray steel coffin after the war and was buried in a clover-covered family plot.

But in 2020, Mr. Martin got a phone call from the Marine Corps. There had been a mistake, he was told: His uncle — Capt. Edward Glen Walker Jr. — wasn’t in that gray steel coffin after all. Instead, he had been found in an anonymous grave in a military cemetery in Hawaii.

The woman on the phone said the military planned to return Captain Walker’s remains and try to figure out who had been buried all those years in the captain’s grave.

“I honestly thought it was a hoax,” said Mr. Martin, who was born nine years after his uncle died and is now retired. “But they started describing the evidence, and a shiver went down my spine, and I said, ‘My God, they’ve got my uncle.’”

Improved forensic techniques and DNA testing can now reliably identify war dead that the military once thought would remain forever anonymous. But the advance comes with a twist: The same technology that can name the nameless can also reveal mix-ups and blunders that caused service members to be buried in the wrong graves.

After World War II, the U.S. military had to sort out the remains of nearly 300,000 war dead. Most were sent home to families or buried overseas in marked graves. But about 8,500 sets of remains could not be identified at the time. These were buried in American military cemeteries under precise rows of marble markers bearing only the word “Unknown.”

For years, those tidy rows have concealed a messy history. The identification process was at times so haphazard and ham-handed that it left identifiable men unaccounted for, or worse, sent them to the wrong families.

Digging into that tangled past can sometimes yield more questions than answers — as it has with Captain Walker.

The arm of the Defense Department in charge of identifying war dead — the Defense MIA/POW Accounting Agency — opened a grave in Hawaii in 2017, hoping to cross a name off the list of 104 men still missing from combat on Tarawa. Instead, researchers found the captain, who was not on the missing list.

And when the steel coffin in Captain Walker’s grave was lifted from the red Tennessee clay and pried open in 2021, things grew even more complicated. Inside, wrapped in a pristine white wool U.S. Navy blanket, was the neatly articulated skeleton of what appeared to be half a man: most of a left arm and leg, ribs, vertebrae and a skull. But DNA analysis revealed a few months later that the bones belonged not to one man, but to at least three. Those remains have not yet been formally identified.

Instead of crossing an individual off the missing list, the effort added three more.

In recent years, similar findings have prompted the government to exhume misidentified war dead in Mississippi, Pennsylvania, New Mexico, Maine and even one at West Point, where the agency quietly opened a grave in 2019. The headstone said it was the grave of a World War II first lieutenant named Ira Cheaney, but a classified 1950 Army memo warned that it probably held the wrong man. Researchers were hoping to find a long-lost Medal of Honor recipient named Alexander Nininger, but the DNA from the exhumed remains didn’t match either man.

Another name for the missing list.

The agency has long known that World War II-era graves probably held a quagmire of past mistakes. A confidential memo clipped to scores of classified files concerning the dead from Tarawa warned of “difficulties” in the burial process and cautioned that each of the graves marked “unknown” might hold a mixture of remains from several people.

In part for that reason, the agency for years steered clear of trying to identify remains in those graves, and focused instead on field expeditions to recover missing American dead from overgrown jungle foxholes or remote airplane crash sites — expensive efforts that resulted in few identifications.

That changed after 2015, when Congress, frustrated with the slow pace of recoveries, mandated that the agency nearly triple its output to at least 200 identifications a year. The only way to do it was to dig into the unknown graves.

The agency has since opened more than 1,000 graves from World War II and the Korean War, and has made hundreds of new identifications. But as the agency acknowledges, it has also frequently found remains that were mixed, mismatched and misidentified, though it would not give a figure for how many.

“As technology advances, we will sometimes encounter mistakes from the past,” said Dr. John Byrd, the agency’s laboratory director. “We attempt to correct it in real time as the case progresses, to include full transparency with the affected families.”

Captain Walker’s case and others like it reveal just how tough it can be to untangle the mistakes of the past.

“The whole thing is fubar, to use a term from the time,” said John Eakin, a Vietnam veteran whose cousin, Pvt. Arthur Kelder, who went by the nickname Bud, died during World War II in a Japanese prison camp in the Philippines called Cabanatuan, along with 2,700 other men. About 1,000 have never been identified.

Mr. Eakin, a longtime aviation crash investigator, concluded from his own research that his cousin probably was buried in unknown grave A-12-195 at the American military cemetery in Manila, and sued the agency to open that grave in 2014 and test the remains.

But it wasn’t a simple matter. Prisoners who died at the camp were initially buried 10 at a time in mass graves. After the war, low-ranking American troops with little training tried to sort them out, but remains were often overlooked, mislabeled or commingled, and, Mr. Eakin said, families were sent remains based on little or no evidence.

“I don’t want to pick on untrained G.I.s, because I’ve been one,” Mr. Eakin said. “But this thing was so fouled up that if they got one ID right, it was just dumb luck.”

Army records suggested that the coffin that Mr. Eakin believed to contain his cousin might actually hold a mix of 10 soldiers. Finding all of Private Kelder, the agency decided, meant digging up nine additional coffins. But it wasn’t so straightforward. DNA tests eventually revealed that the 10 coffins held the bones of at least 15 men — including four who, like Captain Walker, were already thought to have been identified and sent home.

More names for the list.

Hoping to assemble complete sets of remains from the prison camp, the agency uncovered more mix-ups that required yet more digging. Since 2014, the agency has exhumed 311 graves associated with the camp.

This is a uniquely American approach. No effort by other nations that fought in World War II rivals the scope or cost of the Accounting Agency, which has a $130 million annual budget. Other nations generally have chosen to leave the complex realities of combat buried.

Few battles were as vicious as Tarawa. About 18,000 Marines stormed the atoll, which had been fortified by the Japanese, but their landing craft hit reefs far from shore, and the Marines had to wade in through withering machine gun fire. More than 1,000 were killed, along with 4,600 Japanese. Captain Walker, who was voted “most likely to be Chief Justice of the Supreme Court” by his high school class, was found at the water’s edge. On Christmas Eve 1943, his mother got a telegram that began, “Deeply regret to inform you …”

By that point, his body had already been buried hastily with hundreds of others in a field cemetery. As the war churned on, the small atoll became a major U.S. air base, and some field cemeteries were paved over. Only half of the bodies initially buried on Tarawa were located again immediately after the war, and many were only partially recovered.

It’s not clear at what point the military lost track of Captain Walker, said Hannah Metheny, an agency historian who worked on the case: “It could have happened a lot of places, honestly.”

In 1946, crews of low-ranking soldiers toiling in the tropical heat moved all the remains they could find on Tarawa to a central cemetery, and then to the military’s forensic laboratory in Hawaii a few months later.

One set of remains had Captain Walker’s dog tags; another matched Captain Walker’s height, age and gold dental work but had no dog tags. The set with the dog tags were sent to his family in 1947; the set with the distinctive dental work was classified as “unidentifiable” and buried as an unknown.

Captain Walker might have stayed lost, but in 2013 a private nonprofit group of archaeologists called History Flight started digging on Tarawa, and soon it uncovered thousands of bones, which the group sent to the accounting agency. Assembling and identifying full sets of remains would mean comparing the new discoveries with the unknowns from Tarawa that were already in Hawaii, so the agency started exhuming the unknown graves in 2017. Researchers soon found a body that didn’t match any of the missing, but clearly matched someone who had supposedly already been found: Captain Walker.

Lebanon, the town he hailed from in Tennessee, treated the discovery as a homecoming. In 2021, his coffin, draped with a flag, was escorted to the cemetery by hundreds of veterans on motorcycles. Cousins who in some cases had not seen one another in years watched as an honor guard fired a 21-gun salute.

Lane Martin said in a recent interview that he bore no bitterness over the mix-up. He remembered how the loss of his uncle, a promising young law student, had devastated his mother and grandmother, and knew that they took some solace from believing that he was resting in the family plot.

“Even if it wasn’t true, that doesn’t change anything,” Mr. Martin said. “Knowing he was home brought them a lot of comfort. These men that were in the grave all these years gave that to my family, and I thank them for it.”