For the next six months, Noah did not. Instead, he began to dig. Between February and July, Noah and his team were on Tarawa almost continuously. Finally, in August, Noah flew to Hawaii to reveal his results to Johnie Webb. “I didn’t even want him to come to JPAC, because I didn’t want him to get attacked again,” Webb told me. Instead, Webb brought the commanding general of the unit, Kelly McKeague, to meet Noah at a Chinese restaurant. Over lunch, Noah revealed that he had begun to dig on his own. He had filled seven large cases of material for JPAC — including dog tags, boots, ponchos, helmets, ammunition clips and the skeletal remains of at least 50 U.S. Marines.

Webb laughed when he recalled the conversation, but he said the prospect of telling Belcher filled him with dread.

Belcher’s response surprised him. “I said: ‘You know what? We can’t stop him,’ ” Belcher recalled. “ ‘Let’s see what he’s doing.’ ”

Now Belcher and Noah were back on the islands, standing over a box of bones. We piled them into the car and set off down the road. From the size of the cranium and the shape of the grenade, both men were beginning to suspect that the skeleton was not American but Japanese. But they wanted to find out where the bones were found. Nearly everyone who lives on Tarawa has dug up bones at some point. The water table is only a few feet deep, so nothing is buried deeply. With so many skeletons being found and reburied, year after year, the bones can get mixed up. A Japanese cranium could be intermingled with American remains.

We drove through a series of shacks built from sticks and logs. Most were only a few feet square, with open sides and a slag of thatch on top to slow down the rain. Seventy years ago, none of this was there. The construction crews that razed the landscape and covered over the graves erected a number of stark geometric cemeteries lined with white crosses — but these were largely symbolic. The unit that came to exhume the graves in 1946 quickly discovered that most of the crosses weren’t placed over actual graves. “These ‘cemeteries’ were placed without any relation to the actual burials,” the leader of the ’46 recovery team, First Lt. Ira Eisensmith, wrote in his report on Tarawa. Many of the skeletons that Eisensmith and his team found were missing their hands and feet. Noah, who has studied the postwar report, questions its accuracy. “It’s a real C.Y.A. report,” he said. “It says that many of the Marines were buried without their dog tags, and that’s not true, because we’ve been recovering their dog tags. And it says that many of the dog tags were illegible, yet that’s not true — we’ve recovered many legible dog tags 70 years later.” Noah suspects that most of the Marines were intact when they were buried, and that Eisensmith’s team did incomplete excavations that left some of the remains in the ground. “I’m not one to make a big deal about it,” Noah said, “but the people that did this recovery work did a terrible job.”

The conditions on Tarawa today only complicate the process further. Tarawa is one of the most impoverished and overpopulated atolls in the Pacific. The main island, Betio, has more than 20,000 residents, crammed into about half a square mile, which is roughly the population density of Hong Kong. With this overpopulation comes environmental crisis. Garbage is strewn across the beaches and neighborhoods, along with human waste. Many islanders use the beach as a toilet, which pollutes the aquifer and the sea. Outbreaks of typhoid, hepatitis and tuberculosis, along with increasing incidents of leprosy, have struck in recent years, making life for islanders grim and recovery work all the more difficult.

Half a mile down the road, we turned into a dusty lot. This was the neighborhood of a man named Kautebiri Kobuti, who leads Noah’s crew on the islands. Kobuti was in the yard taking a shower with a jug of water. He explained that the bones in the cardboard box had been excavated by his friends. We drove to their house, where four men stood around the edge of a sandy pit while a fifth worked the bottom with a wood-handled shovel. Noah jumped into the pit and examined the ground. After a moment, he stood up with a small bone balanced on a leaf. “Just a fish vertebra, right?” he asked.