Ethel Rosenberg may have been innocent, according to the newly released 1950 grand jury testimony of David Greenglass, who helped cement the executions of his brother-in-law and sister Julius and Ethel Rosenberg. The document offers new evidence that Ethel was innocent in the most intense spying case of the Cold War.

Rosenberg and her husband Julius were put to death in 1953 after being convicted of conspiring to pass secrets about the atomic bomb to the Soviet Union, though they maintained their innocence until the end.

Historians and lawyers who reviewed the transcript said it appears to lend support to both sides of a dueling narrative: Ethel Rosenberg was framed in an overzealous prosecution even as her husband appears to have played a central role in a sophisticated spy ring, reports The Daily Herald.

At the trial, Greenglass, who had been an Army machinist assigned to Los Alamos, N.M., where the atomic bomb was developed, testified that in Sept. 1945, he had delivered bomb secrets to his brother-in-law in the Rosenbergs' Lower East Side apartment. There, he said, his sister typed his handwritten notes for delivery to the Russians.

Years later, Greenglass, who served almost a decade in prison for his role as a spy, acknowledged that in 1951 he could not recall who had typed the notes, and that he actually thought his wife had, but when she remembered shortly before the trial that it was Ethel Rosenberg, he was not going to disagree.

The 46-page transcript of Greenglass's Aug. 7, 1950, grand jury testimony did not include any mention of the typing, nor even of the September 1945 meeting in the Rosenbergs' apartment, reports USA Today.

Greenglass's grand jury testimony about his sister does not necessarily contradict his trial testimony, as it has no mention of typing, but it might have undermined his credibility had it been available to defense lawyers at the time, reports The New York Times.

Greenglass, who was released from prison in 1960, died in 2014. Over the objections of his family and the government, the judge ordered in May that his testimony be made public.

Michael and Robert Meeropol, the Rosenbergs' sons, while acknowledging that their father was legally guilty of the actual charge against him, maintain that he - much less their mother - did not deserve to be executed. "It's not 100 percent proof that the September espionage meeting never took place, but it's a strong indication that it didn't," Robert Meeropol said Wednesday.