Having closed in on the Greenglasses and the Rosenbergs, they were coming closer to Juilus's acquaintances who were equally devoted to leftist politics. Joel Barr, Rosenberg's college friend, disappeared all of a sudden from Paris on the very day Greenglass was arrested. He left hurriedly, leaving all his personal possesions behind. A few days later, another college friend, Morton Sobell boarded a plane with his family at La Guardia Airport. They left for Mexico City. Alfred Sarant made a dash by car to the Mexican border with the FBI breathing down his neck. He successfully ducked the FBI surveillance.

A Cleveland scientist, William Perl, was called before the grand jury where he denied ever having known Rosenberg; on account of that statement and other evidence to establish its falsity, Perl was charged with perjury. The fifth acquaintance chose to cooperate with the FBI. Max Elitcher revealed that Rosenberg tried to recruit him to espionage work in 1944. He described an incident in 1948 when he and Sobell had taken a midnight ride to a deserted waterfront street in New York City so that Sobell could hand a 35mm film over to Rosenberg.

His confession warranted Morton Sobell's arrest. The FBI knew Sobell was still in Mexico, and they tracked him down. On the 16th of August, 1950, after a futile attempt of trying to book passage on a freighter to Europe, Sobell returned to his Mexico City apartment. There he found a group of Mexicans who swiftly forced him into a car and drove him 800 miles to the border, where they handed him to FBI agents in Laredo, Texas.

Trial in New York City

A somewhat foreboding and gloomy feeling came forth with March 6th, 1951, as dark clouds gathered in the New York sky. Julius Rosenberg, Ethel Rosenberg and Morton Sobell were called forward for trial. Each was charged with conspiracy to commit espionage - or rather, treason. The US Attorney Irving Saypol was well known with his recent and successful prosecution of Alger Hiss. He told the jury that the defendants "have committed the most serious crime which can be committed against the people of this country (USA)."

"The weapons the Soviet Union could use to destroy us" were delivered to the Soviet Union by the Rosenbergs, Saypol said about their conspiracy. Emanuel Bloch gave an equally forceful opening statement, and asked the jurors to give the defendants "a fair shake in the American way". Bloch adviced the jury not to "be influenced by any bias or prejudice or hysteria".