They were called the "Atom Spies," and 50 years ago this summer, they were executed for giving the secret of the atomic bomb to the Soviet Union. They are the only Americans ever executed for espionage in peacetime.
60 Minutes II broadcast this story two years ago - the first and only TV interview with David Greenglass, one of the key figures in the Rosenberg case.
Greenglass was the star witness for the prosecution against the Rosenbergs - and he also happened to be Ethel Rosenberg's brother. He served 10 years in prison for his actions as a traitor, and then changed his name and dropped out of sight.
As he neared 80, Greenglass decided to break his silence. He talked only after 60 Minutes II agreed to disguise his face and voice.
Greenglass had a lot to say: He admitted that he had lied on the witness stand, and that his false testimony had cost his sister her life. Correspondent Bob Simon reports.
Greenglass never seemed interested in telling his side of the story, and probably never would have, if a reporter named Sam Roberts hadn't spent 13 years tracking him down.
Roberts, who helped 60 Minutes II obtain an interview with Greenglass, wrote a book on the case called "The Brother."
Greenglass says he believes that he will be remembered by history as "a spy that turned his family in." But, he says he doesn't care.
His story begins in the summer of 1950 when the FBI took Greenglass in for questioning. He confessed almost immediately for spying, and quickly implicated Julius, Ethel and his own wife, Ruth. David and the Rosenbergs were arrested. Ruth Greenglass never was charged.
"That's what I told the FBI," says Greenglass. "I said, 'If you indict my wife, you can forget it. I'll never say a word about anybody.'"
It was quite simply his choice, he says today. So Greenglass says he turned on his sister to save his wife. "I would not sacrifice my wife and my children for my sister. How do you like that?"
Greenglass made his choice when America was at war with communists in Korea, and in fear of the Soviet Union, which had recently tested its own atomic bomb.
The four spies were unlikely actors in a Cold War drama: Julius was an unsuccessful engineer; Ethel spent most of her time raising their two young sons; Greenglass was a draftsman and a tinkerer; and his wife Ruth was a wife and mother. All had been ardent communists.
During World War II, Greenglass, then a sergeant, was posted to Los Alamos, the secret army base in New Mexico, where thousands of scientists and soldiers were building the atom bomb. Although he had a low-level job, Greenglass says he knew what was going on.
He says Julius Rosenberg recruited him to spy with a simple sales pitch: "He said, 'We have to help our ally.'" By ally, he meant Russia. "Russia was an ally at the time, and that we have to help them with all the information we get."
Greenglass told the FBI that he gave the Russians sketches and details on the device used to trigger a nuclear blast. But he says he didn't enjoy being a spy.
"I was continually conscious of what's behind me. I didn't enjoy it. I just did it because I said I would," says Greenglass.
Did he realize how dangerous it was? "I didn't really think it was, because I didn't think the Russians were an enemy," he says.
His career in espionage came to an end soon after the war ended. Back in civilian life, Greenglass and Julius opened a machine shop together. They argued over the business, and over Greenglass' growing disenchantment with Communism.
Four years later, Julius warned Greenglass that the FBI was on to them, and urged him to flee the country. Greenglass had a family passport picture taken, but he had no intention of using it.
"I didn't want to leave the United States to go to some hellhole like Russia or China, or wherever the hell he wanted to send me," says Greenglass. Instead, he took a bus to the Catskill Mountains. "I figured I'd find an obscure place. And I see that the FBI is following me. And they lose me."
But he never made it to the Catskills. He went into custody instead. And within hours, he began cooperating with the FBI, sealing the Rosenberg's fate.
He was the star witness for the prosecution at their trial, and he told the jury about his espionage, and described the activities of Julius, Ethel and his wife, Ruth.
He testified that one evening, he and Ruth brought sketches and handwritten notes about the atom bomb to the Rosenberg's New York apartment. After dinner, Greenglass said they set up a typewriter on a folding bridge table in the living room, and turned his hand-written notes into a neatly-typed document for the Soviets.
Prosecutors asked Greenglass who did the typing. He said under oath that Ethel did the typing. His wife, who also took the stand, told virtually the same story.
That story was virtually the only evidence the government had against Ethel Rosenberg. But prosecutors argued that Ethel's typing proved she was an active participant in the spy ring. After the trial, they admitted that without the typing testimony, they could never have convinced the jury that Ethel was anything more than the wife of a spy - and that's not a crime.
Greenglass stuck to his story for 50 years. But now, he has a different recollection of that night at the apartment.
"Julius and Ethel were there, and I think my wife was there, and myself. And he asked me to write up some stuff, which I did, and then he had it typed. And I don't know who typed it, frankly. And to this day, I can't even remember that the typing took place," says Greenglass, who admits he has no memory of Ethel typing the notes. "But somebody typed it. Now I'm not sure who it was. And I don't even think it was done while we were there."
Why did Greenglass lie on the stand? He now says Roy Cohn, an assistant prosecutor in the Rosenberg case, made him do it. Cohn went on to become Joseph McCarthy's right-hand man.
Greenglass says that Cohn encouraged him to testify that he saw Ethel type up the notes. And he says he didn't realize at the time the importance of that testimony.
But the jury knew how important it was, and found both Julius and Ethel Rosenberg guilty of conspiring to commit espionage. Judge Irving Kaufman imposed the death penalty.
Fifty years later, we know a lot more than anyone could have known in 1951. For example, we know that much of what David Greenglass said about Julius Rosenberg is true. It has been verified by other, independent, sources, all of which confirm that Julius Rosenberg was a Soviet spy. We also know that there is very little, if any, evidence that implicates his wife, Ethel, in any illegal activity.
But in the days before the execution, there were protests and vigils in New York, Washington and Europe. The Rosenbergs both claimed they were innocent, and many believed in them. There were a flurry of last-minute attempts to get a stay of execution. And there was no shortage of Americans who felt that justice was being done.
Up until the last minute, the authorities were willing to commute the death sentences if the Rosenbergs cooperated and named names. But they refused and were executed on June 19, 1953 - without ever breaking their silence.
Why did Greenglass think Julius and Ethel maintained their silence to the end? "One word: stupidity," says Greenglass, who holds his own sister responsible for her own death.
But many saw the Rosenbergs as victims, and there was great sympathy for Michael and Robert, their two young sons - orphaned by the testimony of their own uncle.
Greenglass hasn't seen the Rosenberg children since the trial. What would he say to them today? "I would say I'm sorry that your parents are dead," he says.
Would he also apologize for the role he played in their execution?
"No, I can't say that. That's not true," says Greenglass. "I had no idea they're going to give them the death sentence."
In his closing remarks, the Rosenbergs' lawyer said, "Any man who will testify against his own flesh and blood, his own sister, is repulsive, revolting."
Does Greenglass have a clean conscience? "I sleep very well," he says.
He has never visited his sister's grave, but he admits that he has been haunted to some degree by his experience 50 years ago.
"But every time I'm haunted by it, or say something, my wife says 'Look, we're still alive. We have our kids. Everything's OK.'"