WASHINGTON – Sen. Joseph McCarthy used closed-door sessions to winnow out witnesses who might challenge him in the sensational anti-communism hearings of a half-century ago, transcripts unsealed Monday show.

The senators who oversaw the project, Susan Collins, R-Maine, and Carl Levin, D-Mich., unveiled the transcripts Monday in a room where McCarthy held some of his hearings.

Of the 500 witnesses who testified in private, one-third never were called back to testify in public.

“Anybody who stood up to McCarthy in closed session, and did so articulately, tended not to get called up into the public session,” said Senate Associate Historian Donald Ritchie, who assembled the 4,000 pages of transcripts. “McCarthy was only interested in the people he could browbeat publicly.”

McCarthy, a Wisconsin Republican, chaired the Senate Permanent Subcommittee on Investigations in 1953 and 1954 at the height of the Cold War with the Soviet Union. His investigation into communists in the U.S. government, denounced by critics as a witch hunt, spawned the term “McCarthyism” to describe smear attacks.

Composer Aaron Copland, brought before the subcommittee because he had been hired by the State Department to lecture overseas, was one of those never called back for a public session.

When McCarthy asked whether he ever had been a communist sympathizer, Copland replied, “I am not sure I would be able to say what you mean by the word ‘sympathizer.”‘

“Did you ever attend a communist meeting?” McCarthy pressed.

“I am afraid I don’t know how you define a communist meeting,” the composer answered. Copland, who wrote the 1942 orchestral composition “Fanfare for the Common Man,” went on to win the Congressional Gold Medal and the Presidential Medal of Freedom.

Another closed-door witness who never testified in public was Lt. Col. Chester T. Brown, who refused to discuss the case of a former Army dentist who was suspected of being a communist.

“On what grounds?” McCarthy demanded, threatening to cite Brown with contempt. Any man who refused to cooperate with his investigation, McCarthy lectured, “is not fit to wear the uniform of his country.”

Brown stood his ground, citing an executive order that forbade him from discussing loyalty or security cases.

“May I say, sir, as a soldier, it is my duty to obey my military superiors,” Brown said.

David M. Oshinsky, author of the McCarthy biography, “A Conspiracy So Immense,” and a history professor at the University of Texas, called the closed-door hearings “trolling sessions.”

“McCarthy is looking for people who either have a spectacular story to tell, or people he thinks he can break in public, or people he was certain will take the Fifth Amendment” against self-incrimination, Oshinsky said.

McCarthy was angered when Eslanda Goode Robeson, the wife of blacklisted actor Paul Robeson, cited the 15th Amendment as well as the Fifth Amendment in refusing to answer whether she was a member of the Communist Party.

“The 15th Amendment has nothing to do with it,” said McCarthy, noting that this amendment gave blacks the right to vote.

Robeson replied: “[Y]ou see, I am a second-class citizen in this country and, therefore, feel the need of the 15th. … I am not quite equal to the rest of the white people.”

After McCarthy threatened to cite Robeson for contempt, she finally testified that a truthful answer would incriminate her. McCarthy brought her back to testify in public.

“McCarthy thrived on the Fifth Amendment,” Oshinsky said. “He liked nothing better than to ask people very pointed questions, and they would take the Fifth, so he could call them ‘Fifth Amendment communists’ and talk about a larger conspiracy.”

Despite threatening witnesses with contempt of Congress, not a single witness went to jail, Ritchie said.

The transcripts indicate that McCarthy was convinced that many writers, government officials, engineers and secretaries had access to classified information.

The tide began to turn against McCarthy in 1954, when he looked for subversives in the Army. President Eisenhower, a retired Army general, worked to get the hearings televised so the public could see McCarthy’s bullying tactics, Oshinsky said.

“We hope that the excesses of McCarthyism will serve as a cautionary tale for future generations,” Collins said.

The volumes show McCarthy often held hearings in New York City and Boston, subpoenaing witnesses on short notice, and would be the only senator to attend.

Sometimes even McCarthy wouldn’t attend, Ritchie said. McCarthy’s 26-year-old chief counsel, Roy Cohn, would question witnesses.

Oshinsky said communists had indeed infiltrated the government during the 1930s and 1940s, but by the time McCarthy began his investigation that had largely been stamped out.

McCarthy continued hunting for communists in the State Department, Voice of America, U.S. overseas libraries, Government Printing Office and Army Signal Corps. Republicans began to turn on him when he set his sights on the Eisenhower administration.

The Senate censured McCarthy for his tactics in December 1954, and he lost his chairmanship the following month after Democrats regained the majority. Discredited and broken, McCarthy died in 1957 at 47.

That year, the Supreme Court ruled that witnesses don’t lose their constitutional rights when they testify in a congressional investigation. Some historians say that ruling is McCarthy’s most important legacy.