Sobell... was deferred from active military service because he was a top specialist in his field... Sobell was involved in radar engineering and had access to other confidential documents inside GE. Rosenberg recruited him during the summer of 1944 and handled the first two deliveries of documents. Then, very quickly, as with all other members of the secret network, I stepped in to deal with Sobell. The young man I met was of medium height, with dark hair, regular features and expressive eyes. As soon as he spoke, I understood that he was a modest and good person. His simple way of dressing confirmed my impression. When I asked him if he could microfilm his own documents, he replied it was not a problem since he knew photography quite well. At our next meeting I brought him a camera with the necessary accessories and a small stock of film.

In July ANTENNA (Julius Rosenberg) was sent by the firm for ten days to work in CARTHAGE (Washington). There he visited his school friend Max Elitcher, who works in the Bureau of Standards as head of the fire control section for warships... He has access to extremely valuable materials on guns... He is a FELLOWCOUNTRYMAN (member of the Communist Party)... By ANTENNA he is characterized as a loyal, reliable, level-headed and able man. Married, his wife is a FELLOWCOUNTRYMAN. She is a psychiatrist by profession, she works at the War Department. Max Elitcher is an excellent amateur photographer and has all the necessary equipment for taking photographs. Please check Elitcher and communicate your consent to his clearance.

On Wednesday, August 16, 1950, at about 8.00 P.M. we had just finished our dinner in our apartment in Mexico City in the United States of Mexico, and while my wife and I were lingering over our coffee there was a knock on the door. My older daughter opened the door and three men burst into the room with drawn guns and bodies poised for shooting; these men did not ask my name, did not say what they wanted. I demanded to see a warrant, or some other legal process. No reply, except some vague charge that I was one 'Johnnie Jones' and that I robbed a bank in Acapulco in the sum of $15,000,000 was made. Of course, I vehemently denied the charge.

I insisted on calling the American Embassy but without being permitted to do so. They picked me up bodily and carried me down from the fourth floor to the ground floor. In the street I kept shouting for the police. A taxi was hailed and they opened the door; tried to force me into the taxi; when two more men came in and beat me over the head with blackjacks until I lost consciousness. I woke up in the taxi and I was stretched horizontally at the feet of the three men.

When the car stopped in front of a building, they ordered me to get up; they told me to get into the building, but not to make a scene or they would plug me.... we went upstairs, and, we went into an office.

They sat me down and a slim, tall, dark man came over; he looked at me. I asked him what it was all about. He slapped me in the face and told me that they were the ones that were asking questions. At that point I discovered that my head was bloody and my shirt bespattered with blood.

However, they asked me no questions.... We spent in that building from approximately 8:30 P.M. till 4:00 A.M....

At 4:00 A.M. I was moved into a large four-door Packard and seated in the rear with two armed men, one on each side of me. At that moment, the same tall, thin man came to the door and spoke to my guards in English saying to them "If he makes any trouble shoot him."

The driver of the car, who apparently was the leader of the expedition .., told me that they were taking me to the Chief of the Mexican Police for further action. With a number of stops for one reason or another, we drove on until about 6:00 P.M. At that time... the leader tried to make a phone call or he did make one, and he told me that he was trying to get the chief of police. The same thing happened at about 10:00 P.M., and at midnight on August 17th, telling me that he was trying to make sure that the chief of police would be available.

At about 1:30 A.M. we arrived at Nuevo Laredo....

We stopped at the Mexican Customs on the Mexican side of the bridge, across the Rio Grande marking the border. No examination was made of my baggage.... When we reached the bridge... our car was flagged. We stopped and the front door opened. A man entered with a badge in his hand and stated that he was a United States agent and he remained in the car. When we arrived at the United States Customs I was directed to sign a card, arrested after they searched my baggage and myself. They handcuffed me and placed me in jail where I remained for five days, after which time I was taken to New York City.

The prosecution case against Sobell was that he had agreed and conspired to supply defense data for the use of the Soviet Union (he was not charged with atomic espionage). He declined to take the witness stand and called no defense witnesses; although he pleaded not guilty, he seemed almost traumatized by his predicament. He was not only convicted and sentenced to an incredible thirty years' imprisonment (of which he eventually served nineteen), he was also sent to the notoriously brutal Alcatraz federal penitentiary in San Francisco Bay. Sobell was one of the few Americans whose confinement equaled in rigor and protraction that of the Soviet political prisoners of the era.

My appeals counsel have informed me that at every stage of this proceeding, since the trial, the United States Attorney has stressed in oral argument and affidavit, the fact that I did not take the stand in my own behalf, at the trial. It is highly inappropriate in this case that this fact be given any significance whatsoever, for the following reasons....

I wanted to testify on my own behalf at my trial. I did not do so because my trial attorneys insisted that I should not, because (i) of the fact that the case that the prosecution had put in against me was so weak that my innocence was clearly established; and (ii) that it was so clear that I had nothing to do with any atomic espionage conspiracy.. that it would necessarily follow that I would be freed... I now know I should have insisted on telling my story.

I am completely innocent of the charges made against me. The fantastic tale Max Elitcher told about a wild midnight ride to Julius Rosenberg's apartment is untrue... The balance of his testimony against me, which consisted in not a scintilla more than the insinuation by him of a reference to "espionage" in innocent and routine conversations I had had with him, is likewise untrue.

The only other testimony concerning me at the trial related to a trip to Mexico which I made with my family, which had nothing to do with espionage, and which only after the trial did I realize was given significance by court and jury out of all proportion to what the facts actually showed.... to make the record clear, I want to tell the whole story now.

My wife, daughter, infant son and I left New York in late June, 1950 for Mexico City. This was no suddenly developed plan. I had become dissatisfied with my work in the summer of 1949, but I couldn't very well leave then because I was in the middle of a big project at the Reeves Instrument Company, where I worked. I was in charge of the design and manufacture of a special radar computer known as a Plotting Board, and to have deserted it in midstream would naturally have prejudiced opportunities for future employment. During the following year I investigated several positions but couldn't find anything like what I wanted. I was really interested in getting into more basic research or an academic position.

My project was completed by June, 1950. At about the same time my datighter's school term ended, my wife's graduate physics course at Columbia wound up, and my own course I was teaching at Brooklyn Polytechnic Institute... came to its summer recess. None of us had any special ties keeping us in the city, so we decided to go to Mexico... we had been planning and dreaming of such a trip for several years...

I wrote my employer for an indefinite leave of absence, applied for and obtained necessary visas from the Mexican consul in New York... and bought round-trip tickets at the American Airlines ticket office. On the way, I had the customs officials at Dallas examine and make a record of my foreign-made cameras, so I wouldn't have to pay duty on them when bringing them back into the country. In Mexico City, we rented an apartment for a month or two, where the family stayed all the time we were there.

There was one aspect of the trip, however, which differentiated it from a routine vacation. I was not alone, in mid-1950, in having become apprehensive over signs of political intimidation and repression in this country.... Although a scientist, I was not oblivious to political developments, and in fact, in common with many other scientists, saw a danger to my future in the oppressive atmosphere in which we had to work.

In 1951, Morton Sobell was tried and convicted with Julius and Ethel Rosenberg on espionage charges. He served more than 18 years in Alcatraz and other federal prisons, traveled to Cuba and Vietnam after his release in 1969 and became an advocate for progressive causes.

Through it all, he maintained his innocence.

But on Thursday, Mr. Sobell, 91, dramatically reversed himself, shedding new light on a case that still fans smoldering political passions. In an interview, he admitted for the first time that he had been a Soviet spy.

And he implicated his fellow defendant Julius Rosenberg, in a conspiracy that delivered to the Soviets classified military and industrial information and what the American government described as the secret to the atomic bomb.

In the interview with The New York Times, Mr. Sobell, who lives in the Riverdale neighborhood of the Bronx, was asked whether, as an electrical engineer, he turned over military secrets to the Soviets during World War II when they were considered allies of the United States and were bearing the brunt of Nazi brutality. Was he, in fact, a spy?

“Yeah, yeah, yeah, call it that,” he replied. “I never thought of it as that in those terms.”

Mr. Sobell also concurred in what has become a consensus among historians: that Ethel Rosenberg, who was executed with her husband, was aware of Julius’s espionage, but did not actively participate. “She knew what he was doing,” he said, “but what was she guilty of? Of being Julius’s wife.”

Mr. Sobell made his revelations on Thursday as the National Archives, in response to a lawsuit from the nonprofit National Security Archive, historians and journalists, released most of the grand jury testimony in the espionage conspiracy case against him and the Rosenbergs.

Coupled with some of that grand jury testimony, Mr. Sobell’s admission bolsters what has become a widely held view among scholars: that Mr. Rosenberg was, indeed, guilty of spying, but that his wife was at most a bit player in the conspiracy and may have been framed by complicit prosecutors.

The revelations on Thursday “teach us what people will do to get a conviction,” said Bruce Craig, a historian and the former director of the National Coalition for History, a nonprofit educational organization. “They took somebody who they basically felt was guilty and by hook or crook they were going to get a jury to find him guilty.”

The Rosenbergs’ younger son, Robert Meeropol, described Mr. Sobell’s confession Thursday as “powerful,” but said he wanted to hear it firsthand. “I’ve always said that was a possibility,” Mr. Meeropol said, referring to the question of his father’s guilt. “This is certainly evidence that would corroborate that possibility as a reality.”

In the interview, Mr. Sobell drew a distinction between atomic espionage and the details of radar and artillery devices that he said he stole for the Russians. “What I did was simply defensive, an aircraft gun,” he said. “This was defensive. You cannot plead that what you did was only defensive stuff, but there’s a big difference between giving that and stuff that could be used to attack our country.”

(One device mentioned specifically by Mr. Sobell, however, the SCR 584 radar, is believed by military experts to have been used against American aircraft in Korea and Vietnam.)

Echoing a consensus among scientists, Mr. Sobell also maintained that the sketches and other atomic bomb details that the government said were passed along to Julius Rosenberg by Ethel’s brother, David Greenglass, were of little value to the Soviets, except to corroborate what they had already gleaned from other moles. Mr. Greenglass was an Army machinist at Los Alamos, N.M., where the weapon was being built.

“What he gave them was junk,” Mr. Sobell said of Julius Rosenberg, his classmate at City College of New York in the 1930s.

The charge was conspiracy, though, which meant that the government had to prove only that the Rosenbergs were intent on delivering military secrets to a foreign power. “His intentions might have been to be a spy,” Mr. Sobell added.