Editor's Note: Veterans from both sides of World War II join forces to repatriate belongings taken from bodies on the battlefield. Watch CNN International's World's Untold Stories Saturday and Sunday.

Syracuse, New York (CNN) -- On the black sand beaches of Iwo Jima, 18-year-old Marty Connor stood over the body of a dead Japanese soldier. The young U.S. Marine figured it was only a matter of time before he suffered the same fate.

But he didn't dwell on it and he didn't ponder whether the enemy had a family, a hometown, or a name. Instead, he reached into the dead soldier's pack and grabbed his diary. Then he moved on to another body.

Little did he know then that this was a moment that would change his life; that he would spend 40 years reuniting such war souvenirs with surviving relatives of the dead enemy soldiers.

"A lull in the fighting, you scavenge around a little bit," said the now 85-year-old Connor at his home in upstate New York. "In the helmet, you'd find pictures of his family...so I took things like that, just stuck them in my pack."

Once the bloody 36-day battle on the remote Pacific island had ended, Connor had amassed a collection of items like Japanese bayonets, pay records and family photographs.

Picking up the personal effects of dead enemy soldiers was a common practice during World War II.

When he returned home after the war, Connor locked up his souvenirs in a trunk and rarely thought about them again.

But one phone call, a quarter-century later, would change that.

"Some of the Marines were getting back to have a reunion on the 25th anniversary of our landing," said Connor. "I had a call if I'd like to go, and I thought yes, I would like to go back."

Connor returned to Iwo Jima in 1970. On top of Mount Suribachi, he and other U.S. Marines shook hands with the Japanese veterans they had once fought against.

"They suffered, we suffered," said Connor. "We came to tell them what brave soldiers they were... and our people, our Marines, were just as brave."

The diary, photos and other items Connor had taken from Iwo Jima remained locked up at home. But one of his fellow Marines brought his souvenirs with him, and returned them to their owner's grateful and tearful family.

The emotional scene stuck with Connor. A Buddhist monk named Tsunezo Wachi explained to him the deep spiritual significance these items had for the families of the dead soldiers.

How Connor's story teaches forgiveness

As soon as Connor returned home, he opened the trunk for the first time in 25 years.

"I sent back whatever I had, and in most instances, [Wachi] found the families within two weeks after he received whatever I sent."

Among the grateful recipients of Connor's souvenirs was the widow of the soldier whose diary Connor had taken.

"I was pleased," Connor said of Wachi's efforts. "I was pleased because he brought closure to those families, and I helped out."

Connor figured that might be the end of it. But word of his efforts began spreading to other veterans, and soon, packages were arriving on his doorstep. For the last 40 years, he's made it his mission to send these spoils of war back overseas.

Association of Peace and Mourning: War souvenir repatriation or contact Marty Connor direct at mconnor5@twcny.rr.com

Recently, a new batch of souvenirs arrived at Connor's doorstep. He opened the boxes, and spread out the contents on his kitchen table: dog tags, some Japanese currency from the Philippines, and several Japanese battle flags. Among them was a very well-preserved flag picked up on Iwo Jima on February 22, 1945. Written on the flag were several Japanese names, perhaps relatives of the soldier who carried it into battle.

"We have high expectations that we'll be able to connect this with a family, hopefully of the person that was carrying this," Connor said, carefully picking up the flag.

"If we can determine that, and get it back to that family, it gives that family not only closure, but they no longer seem to have the grief that they had for not having heard for these many, many years... as to what happened to their soldier that they sent off to battle and never came back from Iwo Jima."

Connor put the items in a large envelope and shipped it to Japan.

Awaiting its arrival was Masataka Shiokawa, who stepped in to accept packages after Wachi, the Buddhist monk, passed away.

Shiokawa was only a baby when his father was killed while fighting the Americans in 1945. The only thing his family received was a small box with some stones inside -- meant to represent the remains of his father.

For Shiokawa, that wasn't enough. Years of longing for more information about what happened to his father inspired him to dedicate his life to searching for remains and artifacts, with the hope that he might one day find something that belonged to his father.

"In the beginning I was looking for my father's remains and personal effects very hard. But as I started returning things [to other families], I realized that it is not just me who is feeing this way," Shiokawa said.

When he returns something to a family member, "they get pleased as if the person actually came back. They cry and put the [item] at the family Buddhist altar and offer prayer."

At one such altar sits a white shirt, protected in a glass frame. It belonged to Sadaichi Nagamine, a Japanese soldier. But for 60 years, it sat in Marty Connor's home.

"I took it from a pack," Connor remembered. "There were three Japanese who were killed by naval gunfire and I had taken it from the backpack of one of them. And I just threw it in my knapsack and didn't think of it anymore."

Connor didn't think the shirt had any identification on it. So he never bothered sending it back, assuming its owner could never be found. Finally, in 2005, he decided on a whim to box it up with some other items. To his surprise, Shiokawa found small markings on the shirt, and was able to identify the soldier and return the shirt to his family.

"We wanted to have something to value," said the soldier's nephew, Masami Nagamine, kneeling to pray in front of the family altar. "All ancestors of the family are dedicated in here. I wanted him to rest in peace with the rest of the family."

Connor and Shiokawa are humble about their efforts. The two men, from two countries once engaged in a bitter war, don't speak the same language. But they have the same goal -- to bring closure, answers, and a connection to the relatives of Japan's war dead, who otherwise might never have known the true fate of their loved ones.

Shiokawa opened up Connor's latest shipment. Inside were the dog tags, currency and battle flags that Connor had spread out on his kitchen table. Along with Japanese government officials, Shiokawa researched the names on the most promising flag, and was able to identify its owner as Tadao Yamada, who was killed on Iwo Jima. He set out to find one of Yamada's living relatives.

"I think bereaved families appreciate anything that could commemorate the war dead. They have a special feeling towards it," Shiokawa said.

Gesturing to the latest batch of war souvenirs, he added, "I feel like these are gifts from a tragic history."