Another in a biweekly series of stories about the people and events that shaped Washington in the 20th Century.

Mary Stalcup Markward appeared nervous as she made her way into the cramped hearing room on the morning of July 11, 1951. A battery of photographers snapped away while she quietly took her seat. Behind her, the gallery was jammed with reporters and spectators who had come to hear one of the most prolific spies ever to testify before the House Committee on Un-American Activities.

Markward didn't fit the image of a mole. But there she was -- a young mother and homemaker from Fairfax County, only 5 foot 1, looking prim in her rust-colored suit and white sailor hat -- preparing to tell the committee about the nearly seven years she had posed as a loyal member of the District Communist Party.

She was there to name names.

"I can see her face, how innocent she looked," recalls Murrey Marder, a reporter covering the hearing for The Washington Post. "The fact that she was such an average person, that is what was so unusual. This was not some seasoned counterintelligence operative."

Her testimony -- both in prior closed-door sessions and in the public hearings -- was a sensation. Never before had anyone spoken in public with such knowledge about the inner workings of the party. Never before had it hit so close to home for Washingtonians. Markward gave the names of more than 240 past and present party members, providing the names of their husbands and wives and the exact dates of party meetings. When she finished, the crowd gave her a sustained round of applause.

The nation -- especially its capital -- was in the midst of an anti-Communist frenzy at the time of Markward's testimony. Abroad, U.S. troops fought to contain the Reds in Korea. On the home front, FBI Chief J. Edgar Hoover announced that no fewer than 55,000 card-carrying members of the Communist Party lived in the country. Sen. Joseph R. McCarthy, the relentless Communist hunter, ominously declared that 205 of them were working in the State Department. And in a trial that shocked the nation that spring, Julius and Ethel Rosenberg were sentenced to death for passing nuclear secrets to the Soviets.

For most of the period leading up to World War II, being a Communist was perfectly legal, if somewhat provocative. At the height of its popularity in 1939, the party had 100,000 U.S. members. But in the years after the war, Congress passed dozens of laws, most notably the Smith Act, to ensure the loyalty of federal employees by making membership in subversive organizations a crime.

The most pervasive action to weed out subversives was launched by President Harry S. Truman in 1947. Dogged by Republican charges that he was soft on Communism, he created the Federal Employees Loyalty Program. The program established review boards to investigate federal employees and terminate them if there was "reasonable doubt" as to their loyalty. "Reasonable" grounds included associating with known Communists.

By the spring of 1950, some 3 million had been investigated, mainly by the FBI. Of these, 432 were found unfit for federal employment on loyalty grounds, while 2,476 quit while under investigation.

Ordinary lives were scrutinized and destroyed. Attending a rally or car-pooling with a known Communist was enough to warrant attention. Tens of thousands of people suspected of disloyalty were hauled before loyalty committees, which were not obliged to reveal any information they may have gathered against the accused. Once a person was blacklisted, finding new work often was impossible. Neighbors spied on neighbors, and no one was immune from suspicion. Accusers were frequently anonymous -- and often wrong.

"It was a very distressing, very disturbing time," says Marvin Caplan, a local writer and former member of the Progressive Party, which made him the target of numerous FBI investigations.

During the 1950s, Caplan lived in a community east of the Anacostia River called Trenton Terrace. Many of the residents there were idealistic liberals -- ranging, Caplan says, from actual Communist Party members to Truman Democrats. Investigators from the House Committee on Un-American Activities called it "a leftist nest," and many of its residents found themselves targeted by the government.

Abe Bloom, a former member of the District Communist Party and another resident of Trenton Terrace, remembers the extreme lengths the FBI agents would go to in the course of their investigations: "The FBI hounded me like everyone else. They wanted more names. They were even examining people's garbage."

Occasionally, Bloom and his friends would strike back. "One woman I know, whose name I won't mention, she retaliated by putting, how should I say it, [excrement] in with her garbage," he said.

And now here was Mary Markward, testifying at great length and in extreme detail. One typical exchange, about a club called W-37, which she said was a division of the local Communist Party:

Q: "Was this W-37 an underground club?"

Markward: "Its membership was kept under strict security regulations, but it was attached to our city membership."

Q: Would you tell the committee the make-up of this club as you understood it?"

Markward: "This club was composed of men who worked at the Navy Yard in Washington, D.C., and their wives."

Q: "Can you tell the committee the individuals whom you knew to be members of W-37?"

Markward: "Vic Fleisher and his wife."

Q: "What is Vic Fleisher's wife's name?

Markward: "Rita."

Rita Fleisher, who still lives in the Washington area, says she had no knowledge of any "W-37" club. Markward also identified her as a member of the Civil Rights Club and called the club one of a large network of front organizations for the Communist Party.

"If working for civil rights made me a Communist in their eyes," Fleisher says, "then so be it."

In fact, Communists and civil rights advocates often found themselves on the same side of issues. Many people, especially racial and religious minorities, were attracted to the Communist Party's liberal, progressive agenda. The District party platform called for, among other things, the elimination of discrimination against blacks, a shortened workweek, a free public university in Washington and home rule.

Fleisher had come to Washington in the early 1940s in search of work -- part of a wave of Northerners who had moved to the capital during the New Deal and World War II for government jobs. Like many of these migrants, she had grown up in the working-class Jewish enclaves of New York. Coming to Washington, for her, had been something of a culture shock. The capital was still a Jim Crow town.

"I remember getting on a bus with a date," recalls Fleisher. "There was one seat left on the bus so I sat down, next to a young black child in the back. The bus driver, seeing me there, refused to move the bus. He came up to me and asked me sarcastically if that was my child. It was considered quite an insult back then. Of course, it wasn't an insult to me, but it was to him. It was society at that time."

One of Fleisher's many crusades was to picket Hecht's department store, which was open to blacks for shopping, but not for dining. "They would take these people's money, but they wouldn't serve them lunch at their crummy lunch counter," she says.

Despite her denials of party membership, Fleisher's association with communism haunted her for decades. While she was working as a clerk-typist at the National Institutes of Health in the early 1970s, the FBI showed up at her office seeking to question her. They challenged her about one of her former jobs, working for a magazine called Soviet Today. She hadn't listed it on her application. Finally, with the help of the ACLU, she was able to fight the investigation and save her job.

While social justice was part of the Communist Party's platform, it wasn't the only item on the agenda, which also called for the elimination of capitalism and the establishment of a dictatorship of the proletariat. And the local party was fertile ground for recruitment by the Soviets.

"The Soviets used the party for everything," recalls Herbert Romerstein, a former investigator for the House Committee on Un-American Activities. Because the U.S. government had exposed most of their best agents, they "had to reestablish penetration, so they went lower into the ranks [of the local party]."

It was Mary Markward's increasing realization that some in the party wished to undermine the U.S. government that made her such a zealous undercover agent. "One of the things that people don't understand," says her daughter, Christine Markward O'Sullivan, "is that there were some people who did not have the best interests of the United States at heart."

Mary Markward was just 21 years old and recently married when she was called upon to spy in 1943. A week after her wedding, her husband, George, had been shipped off to Europe to fight in the war, and she was working in a small beauty shop on Massachusetts Avenue to make ends meet. It was there, she told the committee, that she was approached by an FBI agent.

Though she did not reveal the exact nature of their talk, it was commonly assumed that she had been approached because several of her clients were thought to be party members. Her daughter, however, believes it may have been an award-winning essay that Markward had written on why she was proud to be an American that attracted the FBI. The essay was published in a local paper while Markward was still a teenager.

"I considered what he told me over some time," Markward told the committee about her meeting with the agent, "and came to the belief that I could be of assistance to the government by joining this organization, the Communist Party, in Washington, D.C., and furnishing information of what I found out to the Federal Bureau of Investigation."

In May 1943, Markward, using her maiden name to avoid involving her husband, knocked on the door of the local party headquarters at 527 Ninth St. NW -- just two blocks from the FBI building -- and signed up.

"At first, they wondered why a girl from Virginia wanted to accept their program so readily," she testified. "But I convinced them that I was sincere."

She rose quickly within the ranks, eventually becoming treasurer of the District party. She attended citywide meetings and protest rallies and collected party dues and maintained registration rolls. She reported all of this to the FBI on a daily basis.

"I was told several times . . . that the party did not really believe a peaceful revolution could be obtained in the United States," she testified.

Nearly seven years undercover was a strain. She quit her job at the beauty salon in order to devote herself full time to her efforts. From 1943 to 1950, she received about $24,000 from the FBI, mostly to cover expenses. She was ostracized by her family, and friends and neighbors snubbed her because of her new associations.

"I just severed all relations with my old friends," she later told a reporter. "It was tough . . . but, after all, what could you expect? I was publicly proclaimed a Communist in the papers."

"There wasn't anyone who could have loved her country more," says Markward's daughter, "but living a double life for seven years was a terrible ordeal . . . never knowing if or when you were going to be exposed." Her service to the FBI ended abruptly when she was stricken with multiple sclerosis.

Abe Bloom was employed at the Bureau of Standards when his name was given by Markward at the hearings. He recalls the shock he felt when he learned that she was the informant. "We trusted her," he says. "I know people who loaned her money. I know one doctor who was a member of the party, who helped her recover when she was stricken with multiple sclerosis."

Bloom denied being a member of the Communist Party, he says. "The head of the [Bureau of Standards], Dr. Condon, even came down to testify in my favor. But the hysteria was so great at the time, I was fired anyway. If you were blacklisted, you couldn't find another job in your field."

The local press published the names, addresses, occupations and relations of everyone Markward named. Many people lost their jobs and endured years of government harassment.

Maurice Braverman, a Baltimore lawyer named by Markward as an active Communist, was representing Harold Round, another accused Communist, during the House committee hearings. When the committee offered Braverman the opportunity to respond to Markward's charge, he was indignant: "I wouldn't have an answer to any stool pigeon."

"You may regard her as a stool pigeon," responded Rep. Francis E. Walter, a member of the committee, "but I regard her as a great American.

Lillian Clott, also identified by Markward as a Communist, stated that she was not prepared to respond to the charge. "It is impossible to answer such questions," she said, "when you hold that the very asking of them is wrong, and unlawful, and subversive of democracy."

When Markward was finished testifying, the committee members complimented her on her courage and fortitude. Rep. Charles E. Potter, a wounded and decorated veteran of World War II, declared that she deserved a medal for gallantry as much as any man on the battlefield.

But as time went on, things didn't go too well for Markward, either. Despite numerous death threats and her poor health, she continued as a star witness at congressional hearings for years after her appearances before the un-American activities panel. Her country, however, wasn't always grateful. Hoover refused to acknowledge her employment by the FBI, and the IRS came after her for the money she had earned as a spy, forcing her to take out a loan to pay off the taxes she couldn't report without risking exposure. She died in 1972.

"My mother was a great patriot," says her daughter. "They could have treated her better."

CAPTION: Mary Markward is sworn in before the House Committee on Un-American Activities in 1951.

CAPTION: Mary Markward, in white hat at lower left, testifies before a packed hearing room during a 1951 session of the House Committee on Un-American Activities.

CAPTION: In the 1940s and 1950s, the Communist Party office in Washington was in a building on Ninth Street NW, just two blocks from the FBI headquarters.