Based on this article his wife was innocent and he was guilty.
She knew who and what her husband was. She might as well have driven the getaway car.
I’m the co-author of the book The Rosenberg File, sometimes cited as the source for the notion that Ethel Rosenberg was innocent. Not so. Julius was the organizer of the spy ring. Ethel was aware of what he was doing and occasionally acted in an accessory role. At times, however, her help was very important — as when she talked her brother David Greenglass into contributing information about his work at Los Alamos.
It seems Ethel was also ready to volunteer for other tasks. Before the Soviets brought in Harry Gold as courier it was suggested in the Rosenbergs’ correspondence that Ethel would travel to New Mexico to pick up data.
There is no question that Ethel would have received a lesser sentence if Julius had confessed. Even in the absence of a confession, many observers — including J. Edgar Hoover — thought she should have been sentenced as an accomplice. But innocent she was not.