She served the Soviet Union as the primary handler of multiple highly placed moles within both the United States Federal Government and the Office of Strategic Services from 1938 to 1945.

Bentley became widely known after testifying as a prosecution witness in a number of trials and before the United States Congress' House Un-American Activities Committee (HUAC).

Golos needed someone to take charge of the day-to-day business of the United States Service and Shipping Corporation, a Comintern front organization for espionage activities;[20] Bentley took on this role as well.

This intelligence included secret estimates of German military strength, data on U.S. munitions production, and information on the Allies' schedule for opening a second front in Europe.

[25] In early June 1944, Browder acceded to Akhmerov's demands and agreed to instruct the members of the Silvermaster group to report directly to the NKGB.

[26] Bentley's biographers suggest that her objections were not ideological, but were related more to a lifelong dislike of being given orders and a sense that the reassignments of her contacts left her with no meaningful role.

[27] She was ordered to give up all of her remaining sources (including the Perlo group) later in 1944, and her Soviet superior told her that she would have to leave her position as vice president of U.S. Service and Shipping.

Bentley's personal situation continued to worsen; she arrived drunk at a September meeting with Anatoly Gorsky, her NKGB controller.

[31] In a series of debriefing interviews with the FBI beginning November 7, 1945, Bentley implicated nearly 150 people (including 37 federal employees) as Soviet spies.

[35] About 250 FBI agents were assigned to the Bentley case, following up leads she had provided and (with phone taps, surveillance and mail interception) investigating people she had named.

The FBI, grand juries, and congressional committees would eventually interview many of these alleged spies, who invoked their Fifth Amendment right not to testify or maintained their innocence.

With chances of successful prosecution looking unlikely, Hoover gave the names of some of Bentley's contacts to members of Congress with the understanding that the accused spies would be questioned by Congressional committees.

Bentley decided to reveal her full story herself to retain more control, and met with New York World-Telegram journalists Nelson Frank and Norton Mockridge.

Bentley was subpoenaed to testify at a public hearing of the House Un-American Activities Committee (HUAC) on July 31, 1948, a few days after the World-Telegram articles were published.

Under subpoena by HUAC, he testified that he knew at least two of Bentley's contacts (Victor Perlo and Charles Kramer) as communists and members of his earlier Ware Group.

Conflicts of this nature, along with fears of Soviet communist power in Europe and the increasingly-publicized HUAC hearings, formed the background of McCarthyism.

The witch hunt for communists initiated by Senator Joseph McCarthy (R-Wisconsin) became a central factor in 1950s domestic American politics.

When she did not, Green filed a libel suit for $100,000 in damages on October 6, 1948, against Bentley, NBC and Meet the Press sponsor General Foods.

Others who denied Bentley's charges were Lauchlin Currie, formerly President Roosevelt's economic affairs advisor; Remington and William Henry Taylor, mid-level government economists; Duncan Lee, formerly of the Office of Strategic Services (OSS); and Abe Brothman, a private-sector chemist who worked on defense projects.

They produced evidence of alcoholism, periods of severe depression, and a suicide attempt as a student in Florence; alleged that her master's thesis had been written by someone else, and she had been sexually promiscuous (by the standards of the day) since college.

[54] Bentley said that her espionage gave her advance notice of the Doolittle Raid on Japan and the D-Day invasions of France; both claims were apparently exaggerated.

Roy Cohn, later chief counsel for Senator Joseph McCarthy's Government Operations Subcommittee and already a prominent anti-communist, joined the prosecution's legal team.

We also discovered Remington's application for a naval commission in which he specifically pointed out that he was, in his present position with the Commerce Department, entrusted with secret military information involving airplanes, armaments, radar, and the Manhattan Project (the atomic bomb).

[56]Eleven witnesses testified at the trial that they knew Remington was a communist, including Bentley; his ex-wife, Ann Remington; Howard Bridgeman of Tufts University; Kenneth McConnell, a communist organizer in Knoxville; Rudolph Bertram and Christine Benson, who worked with him at the Tennessee Valley Authority; and Paul Crouch, who provided him with copies of the southern edition of the Daily Worker.

[60] Bentley wrote in her autobiography, Out of Bondage (1951), that she had been "able through Harry Dexter White to arrange that the United States Treasury Department turn the actual printing plates over to the Russians".

[61] She elaborated in 1953 to McCarthy's Senate subcommittee, testifying that she was following instructions from NKVD New York rezident Iskhak Abdulovich Akhmerov to pass word through Ludwig Ullmann and Silvermaster for White to "put the pressure on for the delivery of the plates to Russia".

Gaik Ovakimian (head of the NKVD's American desk) cited an April 14, 1944, report in the memorandum that, "following our instructions" via Silvermaster, White had "attained the positive decision of the Treasury Department to provide the Soviet side with the plates for engraving German occupation marks".

[66] Bentley was asked to testify before a number of bodies investigating communist espionage and influence in the U.S. after her defection, and continued consulting occasionally with the FBI for the rest of her life.

According to Kathryn S. Olmsted, Bentley received frequent requests from Catholic and veterans' groups "happy to pay her $300 fee" for a lecture.

[76][unreliable source] Bentley provided no documentary evidence to support her claims, and reporters and historians were divided for decades about the validity of her allegations.