The National Park Service and the Vietnam Veterans Memorial Fund preserve items people leave at the Vietnam Veterans Memorial. (Dakota Fine/The Washington Post)

The black and white snapshot of the seven enemy soldiers was left in a box at the Vietnam Veterans Memorial with a two-page letter.

The writer explained how he had grabbed the picture from the knapsack of a dead North Vietnamese soldier after cursing him, kicking him and firing into his corpse in a fit of rage.

The veteran, who was 20 at the time, in 1969, had lost a close friend in battle six days earlier, and his outfit had just ambushed and killed 40 enemy soldiers, including this one, in a “turkey shoot.”

Forty-two years later, the former “grunt” came to the Wall in Washington on a chilly fall morning. He put down the box and, weeping, read his letter aloud.

“I come here today in sadness and humility, the arc of my life having transformed me from the angry young man who desecrated your body to an older man seeking peace. . . . Please forgive me, my brother, and rest in peace.”

Over the past three decades, the Wall has become a hallowed spot, a place of pilgrimage, homage and reconciliation. Now, some of the 400,000 items left there over the years by visitors are being selected for display in the new $115 million Vietnam War education center planned for a site nearby.

For the past 21/2 years, experts have been combing through the things that were left at the Wall since it was dedicated in 1982 and that were later stored in a National Park Service facility in Maryland.

Letters, dog tags, college rings, a football helmet, a motorcycle, posters, sneakers, cigars, medals and a piece of a helicopter rotor blade are among the things that make up what is now the Vietnam Veterans Memorial Collection.

They fill hundreds of bright-blue storage boxes stacked on long rows of shelves in the Park Service’s Museum Resource Center.

Items such as the “care package” wrapped in brown paper that was sent to a U.S. soldier, Charles L. Stewart Jr., in Vietnam in 1972 have been selected for display.

Stewart, 19, had been killed by the time the package arrived, and it was returned to his family in Gladstone, Mich., marked “KIA,” killed in action, “10-31-72.”

A person who curators said may have been a brother left it at the Wall in 1993, with a note.

A war trophy (a snapshot of North Vietnamese soldiers) taken from the body of a North Vietnamese soldier by a U.S. Army soldier. (Michael S. Williamson/The Washington Post)

“Mom and Dad want you to have these cookies and Kool Aid. . . . They send all their love.”

On Oct. 1, 1990, the mother of another soldier who had been killed left the knitted sweater that he had worn as a baby and a handwritten letter:

My Dearest Son,

Today I am coming to see your name on the “wall.” I haven’t been ready until now, but I know that I must see it before I die. . . .

I wanted to bring your teddy bear but just couldn’t part with it. Instead I brought your first sweater. You are always in my heart. . . .

God be with you til we meet again.

Love,

Mom.

No one anticipated that visitors would leave tributes when the memorial was dedicated 33 years ago. But the black granite Wall, where the names of 58,000 killed in the Vietnam War are etched, has become a place where spirits seem to reside.

The veteran who left the box and 40 years of anguish at the Wall called it “a very sacred place, very holy.”

Now in his 60s, he recently agreed to tell the story of his encounter with the Wall, but he spoke on the condition that his name not be used, because of the sensitivity of his account.

His is one of thousands of stories of grief, love, loss and reconciliation.

“There is no sociological or anthropological precedent in the United States for that kind of behavior, until the Wall was built,” said Jan C. Scruggs, whose Vietnam Veterans Memorial Fund created the memorial.

“The Wall gave people the license to mourn publicly and to start bringing things,” he said. “There’s something very profound about it, feeling the connection between the living and the dead, feeling the way we still love and care for people.”

The legend is that the first object left was a Purple Heart medal, which was placed at the cornerstone of the Wall, said Jason Bain, a senior collections curator with the memorial fund.

As more things were left, park rangers stored them in boxes in their offices, and as the volume increased, the Park Service realized the importance of what was being left, Bain said.

The formal collection was established in 1984. The items numbered about 1,300 then. Four years later, there were 12,000.

“We will have researched about 30,000 to 35,000 by the time my portion of the project is complete,” he said in an interview last month. “We will have selected . . . about 6,000” available for display.

Bain said most of the items left at the Wall lack provenance — experts don’t know who left them or why.

But in some cases the details are clear.

The young American soldier was searching for enemy bodies at night when he came across the dead North Vietnamese by the light of illumination flares.

The American and his comrades had just surprised a group of about 90 North Vietnamese soldiers walking down a trail and “slaughtered” about half of them, he would later write.

He had been in Vietnam for about six months as an “11-bravo,” a front-line infantryman, in the Mekong Delta, south of Saigon, now Ho Chi Minh City.

He had seen a lot of action, had been badly wounded and was devastated when a sniper killed his sergeant a few days earlier.

He had helped pull the sergeant out of the line of fire. “I’m gonna die,” the sergeant said. “We said, ‘No, no, you’re okay. We’ll patch you up,’ ” the soldier recounted in the interview.

Later, the pilot of the helicopter that carried the sergeant to Saigon radioed back that he was “delta, oscar, alpha,” dead on arrival, he said.

So when the American found the enemy soldier’s blood-soaked body in a rice paddy, he was not in a forgiving mood.

“I savagely kicked your leg, flicked the safety off of my weapon, and fired point-blank into your head.

“I was itching for revenge and this is how I would get it.”

He noticed that his foe’s knapsack was partially open, so he rummaged through it for a trophy, some proof that he had exacted retribution. He pulled out the snapshot, two small flags and what turned out to be a poem.

He stuffed them in a pocket and “returned to the gruesome tallying of our body count.”

Six months later, his tour ended. He left Vietnam, placed the trophies in a footlocker, and later in a wooden box, and put them away. He got married, started a family and found a good job.

But he was chronically troubled by memories of the war.

And the contents of the box haunted him.

Sometimes he would pause to look inside.

“I felt like I was looking into some forbidden abyss within my soul. An unnamable feeling would jolt my heart and I would close the lid.”

The snapshot was especially difficult.

The seven young North Vietnamese soldiers posed in uniform, standing on the slope of a small hill. They wore distinctive pith-type helmets. An eighth man, clad in black instead of a uniform, stood behind them to their left.

They were clearly a squad of soldiers, the American realized, much like the U.S. Army squads he served in.

“I examine the photo closely, looking at each face and wondering which one was you, trying to imagine the unfathomable grief of your mother and father.”

In the years after the war, the soldier said, “I had a classic, classic, terrible case of PTSD. I kept saying to myself, ‘What’s wrong with me? Why can’t I readjust? Why can’t I come home and just sort of forget about that?’ But I couldn’t.”

He pored over books about war — the Civil War, World Wars I and II, Vietnam — searching for clues to his pain.

Decades passed. Finally, seven or eight years ago, he started going to counseling. “I began to understand my journey, where I had been, who I was,” he said. Many things got resolved.

“But there was one deep dark secret that was sitting right in my closet,” he said. “I knew it was in there. I felt its presence.”

When he was ready, after more counseling, he sat down and wrote the letter. Then he asked his wife, who was unaware of the box, to come to a counseling session with him.

There, he opened the box and read the letter.

It began, “I came upon your body, lit by the ghostly glare of illumination rounds . . . .”

Afterward, he realized that the contents of the box belonged at the Wall. “I don’t know where it came from, but it was my idea,” he said. He told his wife: “I can’t keep these in my closet any more.”

One day near dawn in 2011, he and his wife went to the Wall with the contents in a nicer box that they had bought. It was cold outside, and the sun was just reddening the sky over the Capitol. The soldier could see his reflection in the polished stone.

He found his old sergeant’s name on the Wall. Then he read the letter aloud.

“I cried,” he said. “I wept, I keened, in a way I never have before. I felt an enormous release, a weight off my soul . . . [and a] peace and a calm . . . that I’ve never known.”

He placed the box against the Wall and propped the letter behind it. As he and his wife walked away from the memorial, he glanced back.

“The day was dawning,” he said. “It literally felt like a new day for me.”