LOS ANGELES >> Every morning, she climbed the wide marble steps of the National Archives in Washington, D.C.

Aiko Herzig-Yoshinaga was not trained for this work. She was a homemaker, not a historian. But she had a lifetime of simmering anger and unanswered questions.

By lamplight in the grand reading room, she scoured thousands of documents, inventing her own organizing system to keep track of the information. She brought home so many copies that she commandeered a bathtub and used it as a filing cabinet.

Eventually, after years of labor, she happened upon files that would help correct injustices committed during one of the darkest periods of American history — and of her own.

These days, she works at the dining room table at her home in Gardena, Calif.

Now 86, she is busy finishing a book of first-person remembrances of the Japanese-American experience in World War II. Asked about her deadline to finish the book, she lets out a low laugh.

“Yesterday,” she says.

Her home is quiet and light-filled, with Japanese screens and a budding fuchsia orchid. Scattered about are bankers boxes packed with files.

She sits surrounded by papers, reading and taking notes until long after the sun goes down. Behind her, a black-and-white photograph hangs on the wall — a reminder of what drives her.

It shows a dust-blown desert and rows of wooden barracks.

———

In 1941, Aiko Yoshinaga was 17, a senior at Los Angeles High School. She loved roller skating and swimming with her friends at Santa Monica Beach. She was looking forward to prom.

Then Imperial Japan bombed Pearl Harbor, and the United States was thrust into World War II.

Some officials questioned the loyalty of Japanese-Americans like Yoshinaga, who was born in California but whose parents had emigrated from Japan years before.

After President Franklin D. Roosevelt signed an executive order that authorized the forced removal of Japanese-Americans from “military areas” in 1942, about 110,000 were rounded up on the West Coast and shipped to internment camps. The government said it was a military necessity.

Her father and mother and her siblings were sent to live in the stables at Santa Anita racetrack before being transferred to camps.

Yoshinaga had eloped with her boyfriend when she learned they might be sent to separate detention centers. The newlyweds were bused to the Manzanar War Relocation Center in the eastern Sierra, 250 miles from Los Angeles.

Like many people of Asian descent living in America in the 1930s and 1940s, Yoshinaga had known bigotry. She had been called names on a city bus and discouraged from starting a Japanese club at school.

But as she lay on an Army-issue cot in Manzanar, a wet cloth draped over her face against the dust that blew relentlessly, she felt the weight of prejudice on a much larger scale.

“We were stunned,” she remembers. “Absolutely stunned.”

———

Behind barbed wire, she grew from a teenager into a young woman.

At Manzanar, she gave birth to a baby. At a camp in Arkansas, where she was sent to visit her ailing father, she watched him die.

After three years, the government closed the camps.

Yoshinaga followed some relatives to New York City with her young daughter, but without her husband. They had divorced after he was drafted to serve in the military in World War II.

She took a secretarial job and tried not to make waves. She eventually remarried and had two more children.

It was only decades later that she began to confront her earlier traumas.

Watching news coverage of the Vietnam War, and especially the killing of 500 Vietnamese villagers by American soldiers at My Lai, she began to question what she saw as the contradiction between American policy and American values.

When a friend invited her to join a left-leaning political group called Asian Americans for Action, she went. At one meeting, someone mentioned the concept of “institutionalized racism.” It was an idea she “had always felt” but had never been able to put into words.

An activist was born — in her 50s. She soon found herself swept up by the causes of the era. She was arrested while picketing against apartheid outside the South African Embassy. At a march calling for a U.S. withdrawal from Vietnam, a heckler shouted, “Go back to where you came from!”

“Where?” she spat back. “California?”

———

In 1978, she was living in Washington, D.C. She had divorced again, and married again.

Jack Herzig was a former U.S. Army paratrooper who had fought the Japanese in World War II and was now working for the Department of Defense as a counterintelligence expert. His new wife was astonished to learn that he knew almost nothing about the internments.

She decided that more people needed to know what their government had done to Japanese-Americans in the 1940s. But first she would have to educate herself.

A friend from New York who had written an acclaimed book about the internments, Michi Nishiura Weglyn, recommended she look through the World War II records at the National Archives.

Every morning, her husband dropped her off there on his way to work. Some evenings, he would join her, and they would pore over documents together until the building closed.

At first, Herzig-Yoshinaga sought information about her family’s experience. Then, on a whim, she asked research librarians to help her locate some of the government documents cited in the footnotes of Weglyn’s book.

She was angered by the language in some of the records, such as descriptions of Japanese-Americans as “enemy aliens.”

Her outrage fueled her research. If she found an intriguing letter from a War Relocation Authority official, she would hunt down the letters that preceded and followed it. If a State Department memo was copied to a group of people, she would ask for the records related to each of them.

“One document led to another,” she said. Soon, she and her husband were traveling the country to visit other institutions that housed records from that era.

When Congress, in 1980, established a Commission on Wartime Relocation and Internment of Citizens, Herzig-Yoshinaga applied for a job as researcher. By that time she had accumulated about 8,000 documents, and she knew the layout of the byzantine National Archives as well as she knew her own kitchen cupboards.

She got the job.

The commission had been created to examine the internment. One day, Herzig-Yoshinaga stumbled upon a report that suggested the policy was based more on racism than military necessity.

Government lawyers had argued that the U.S. rounded up all Japanese-Americans on the West Coast because there wasn’t time to determine who was loyal and who was not.

But the document Herzig-Yoshinaga found, an early draft of a report by Lt. Gen. John L. DeWitt to his Army superiors, said that time had not been the issue. DeWitt wrote that internments were necessary because Japanese cultural traits prevented officials from distinguishing between loyal and disloyal Japanese-Americans — “it was impossible to separate the sheep from the goats.”

Herzig-Yoshinaga’s discovery played an important role in the commission’s conclusion that internment was a product of “race prejudice, war hysteria and the failure of political leadership.”

The findings led to an official government apology and reparations of $20,000 per survivor.

In 1983, lawyers who had reopened the cases of three Japanese-Americans convicted of resisting internment built their cases in great part on research done by Herzig-Yoshinaga.

In the most famous case, Fred Korematsu v. United States, the Supreme Court in 1944 had upheld the internment of Japanese-Americans as a matter of “military urgency.”

Herzig-Yoshinaga and Peter Irons, a member of the legal team representing the three defendants, tracked down transcripts of Solicitor General Charles Fahy’s arguments before the Supreme Court, in which he said the roundup of Japanese-Americans was a matter of “military necessity.”

DeWitt’s draft report suggested otherwise, as did a 1942 naval intelligence assessment that there was little danger of spying or disloyalty on the part of Japanese-Americans.

Thanks in part to Herzig-Yoshinaga’s findings, courts vacated the convictions of Korematsu, Gordon Hirabayashi and Minoru Yasui.

Last month, in an extraordinary admission, Acting Solicitor General Neal Katyal declared that Fahy had trumped up the threat of subversion by Japanese-Americans and had suppressed evidence to the contrary, shirking his “duty of absolute candor” in dealings with the high court.

Civil rights attorney Dale Minami, who worked with Herzig-Yoshinaga on the three cases, said he hoped that Katyal’s acknowledgment would give her and others a sense of vindication.

“But you can’t compensate for the loss of liberty,” Minami said. “You can’t compensate for the loss of the best years of your life.”

———

Her husband died six years ago, and she recently broke her collarbone in a fall. But her research continues.

In 2009, she published a dictionary of internment terminology (in it, she calls for “transparent” phrases, such as “concentration camp” or “gulag,” in lieu of “internment camp”). She has helped friends find documents so they can qualify for reparations.

And there is the book, “Speaking Out for Personal Justice,” a compendium of testimonies taken by the congressional commission. It will be published by the Asian American Studies Department at UCLA.

In her gracious manner, there is not a trace of bitterness.

Several weeks ago, she was honored with the Spirit of Los Angeles award in a ceremony at City Hall.

“The story of this woman is a story of courage,” Mayor Antonio Villaraigosa told the City Council. Herzig-Yoshinaga smiled with gratitude.

“And to think that as a teenager in 1942, I was considered undesirable,” she said with a small laugh.

“What a glorious ending to a life of hard work.”