, david greenglass got a reduced sentence.o had served as a soviet courier, never spent a day in prison. prosecutors believed the prospect of ethel dying in the electric chair would force julius rosenberg to confess and name other soviet spies. >> michael meeropol: in the case of my mother, she really is collateral damage, you know. this is... this is the government trying... you know, putting a gun to her head and saying to julie, "talk or we'll kill her." >> cooper: you don't think she was involved at all? >> michael meeropol: we don't believe that, and, in fact, we believe that the evidence has virtually proved that. >> cooper: after david and ruth greenglass died, their testimony to a grand jury before the rosenbergs' trial was unsealed. there was no mention of ethel rosenberg typing up david greenglass' notes. and when those soviet messages the u.s. had been secretly decoding were publicly released, they showed the soviets had never given ethel rosenberg a code name. in 1997, when julius rosenberg's former soviet handler,

' notes on the atomic bomb. >> greenglass: where do i sit?re? >> yes, sir. >> cooper: in 2001, half a century after he testified that his sister typed up his notes, david greenglass told "60 minutes'" correspondent bob >> simon: so, ethel finally went to the electric chair on the basis of evidence that was false. >> greenglass: false. >> cooper: he said he did it to save himself and his wife, and he showed little remorse. >> greenglass: we're still here. i didn't have to go away. nobody killed me, and i survived. >> simon: your sister didn't. >> greenglass: you know, i'd like to say something. i would not sacrifice my wife and my children for my sister. how do you like that? my wife is more important to me than my sister. >> cooper: greenglass said he was pressed to give this false testimony by one of the prosecutors in the case, roy cohn, who would go on to become senator joseph mccarthy's right- hand man and was later disbarred for unethical conduct. >> simon: did cohn encourage you to testify that you saw ethel typing up the