Tarawa Atoll (CNN) -- United States Marine Corps Staff Sgt. Kurtis S. Witt pulls out a knife and kneels beside a WWII-era Japanese 3-inch projectile. Witt gingerly chips away at corrosion on the still unexploded artillery shell.
As pieces fall off, he gives it several more heart-stopping whacks. Biteti Tentoa, or "Peter," a Betio island native, watches from a safe distance. He jumps back expecting a catastrophic explosion. Nothing happens.
Witt is an explosive ordnance disposal technician with the Joint POW/MIA Accounting Command. This 13-member team has spent the past month on Tarawa, a tiny Pacific atoll straddling the equator, searching for the remains of missing soldiers and Marines from the Battle of Tarawa. Now 67 years later, hundreds of Americans are unaccounted for and buried in mass graves around the island.
The team is digging meticulously, sifting for bone fragments through several meters of sandy soil. Archaeologist Gregory Fox keeps Witt close by. "We do a sweep on a site first to try to locate any ordnance, then he tells us whether or not we can work and keep him real close while we're digging. He's an essential team member for everywhere we work. We don't work in city parks; we work in battlefields."
Meanwhile Tentoa has walked almost 2 miles to the dig site. "We didn't know Marines were coming, just heard over the cocoanut wireless. I go straight to the captain. Do you like to see the body of one man from America?"
Capt. Todd Nordman is the team leader. He drives a small team over to Tentoa's home in the middle of Betio. It's a thatched-roof hut with dirt floors and a hand-dug well. Like most of the Kiribiti villagers, he's poor, barely surviving as a tailor. Once the team arrives, Peter walks Nordman into his home, and his son gently hands Nordman a box containing the remains. Tentoa has kept these remains safe from grave robbers.
"So while we're digging aiming to make a garden," Tentoa says, "we found the body of a Marine soldier from America."
His cap was on his skull, and his teeth were fitted with silver. Tentoa says he found a canteen and an ammo belt next to the bones.
"We're really happy to give the body of the man to the captain of the Marine group because that's our aim, to make the family happy," Tentoa says. He wants to meet the Marine's family.
While Nordman's group is preparing to leave, Tentoa hands over the artillery shell. "We thought only something to play with, only a piece of iron, no use. So when you come and say bomb, we afraid of it. Don't want to leave it in the house" Tentoa says.
Witt examines the fuse of Tentoa's projectile. He estimates it's filled with possibly 2 pounds of high explosive and that an ounce is enough to kill a man.
"This would be like a light artillery piece." Witt says. "It's still in the shell. It's unfired, meaning it's unarmed. This is basically in the same condition the guys that operated this gun system would have picked it up and thrown it into the gun. This one never made it into the gun. So it's safe."
Witt carefully walks the projectile to the back of his truck to "bunker it" in a safe location.
"They're scared of it." Witt says, "They were worried about it. To me this is a simple problem, but to an untrained eye it may be the scariest thing in the world. So bringing my expertise to the table can bring a warm and fuzzy to everybody's minds."
Witt, an Alaska native, comes from a military family. He has a twin brother and two younger brothers also in the service.
His twin Kody is an Army Special Forces diver. His brother Logan is a Marine sergeant in Camp Pendleton, and the youngest, Jesse, is at West Point Army Academy. All have been to Iraq; Kody is serving in Afghanistan.
While all branches of the military participate in the command, Fox specifically asks for as many Marines as he can get.
"Tarawa's pretty much sacred ground in the United States Marine Corps," he says. "It was a telling battle early in the war. The United States learned a lot from this battle, and they've carried on in their traditions."
For Witt it's a highlight of his service. "Being here on Tarawa looking for my Marine brothers does hit a certain spot on the inside. It gives you goosebumps down your spine just thinking about it. Being able to look down that beach and picturing them going through that battle, the intensity of it all.
"It ends up in a mass grave, gets lost, now we're out here. I get to be part of the team that finds them and brings them back to their family, their fellow brothers, and gives them that closure. It's an amazing feeling," he says.
"If one of my brothers went down I'd want them back, too. And it's awesome that we're doing this mission because I now have the confidence when I'm out in combat or one of my brothers is, that no matter what happens, my government's got my back, and whether it takes a year or 60 years, I'm gonna be home...My family is going to get that closure."
Witt secured 20 projectiles at the end of the mission, including 60 mm mortars and several grenades. In several instances, shells were exuding "pitric acid from corroded fuse wells...and this is when stuff can get a little hairy," he said.
When he came across a mortar shell, and high explosive had crystallized, Witt said, "This is when unexploded ordnance is truly in a sensitive state."
The command wraps up its mission in Tarawa this week. While no mass graves were unearthed at six dig sites, they will return with remains that were handed over. Tentoa hopes one day to get a call from a grateful American family.