David Greenglass

WASHINGTON — The brother of Ethel Rosenberg, who was a star witness against his sister and brother-in-law in a sensational Cold War atomic spying case, minimized his dealings with his sister during an earlier appearance before a grand jury and said they had never discussed her role “at all,” according to court records unsealed Wednesday.

The revelation may heighten public suspicion that Ethel Rosenberg was wrongly convicted and executed in an espionage case that captivated the country at the height of the McCarthy-era frenzy about Communist allegiances.

Rosenberg and her husband Julius were put to death in 1953 after being convicted of conspiring to steal secrets about the atomic bomb for 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 — that Ethel Rosenberg was framed in an overzealous prosecution even as her husband seems to have played a central role in an intricate spy ring.

“You change a black-and-white Cold War narrative — framed or traitors — into a very nuanced, gray area,” said Tom Blanton, director of the National Security Archive at George Washington University, which fought for the records.

The grand jury testimony from David Greenglass, whose damning statements at trial helped secure the convictions of the Rosenbergs, had been withheld from public view even as other crucial court records have been unsealed in the last decade. A federal judge in New York ordered the 46-page transcript unsealed following Greenglass’ death last year.

The grand jury transcript opens a window into an espionage operation involving shady operatives, code names and symbols to recognize couriers for the Russian.