The codebreaker Meredith Gardner recalled that Weisband had watched him extract a list of Western atomic scientists from a December 1944 NKVD message.

As Allen Weinstein pointed out, "Soviet intelligence's once-flourishing American networks, in short, had been transformed almost overnight into a virtual clipping service.

From these materials, we came to know that, as a result of this work, American intelligence managed to acquire important data concerning the stationing of the USSR's armed forces, the productive capacity of various branches of industry, and work in the field of atomic energy in the USSR... On the basis of Weisband's materials, our state security organs carried out a number of defensive measures, resulting in the reduced efficiency of the American deciphering service.

Where Weisband had sketched the outlines of U.S. cryptanalytic success, British liaison officer Kim Philby received actual translations and analyses on a regular basis after he arrived for duty in Washington, D.C., in autumn 1949.

While suspended from SIS on suspicion of disloyalty, Weisband failed to appear for a federal grand jury hearing on the Communist Party USA, for which he had received a summons.

Weisband never revealed his status as an NKVD agent to anyone, and he remained in the United States, living quietly, and working as an insurance salesman until his death.

His son describes his death: [My] It was Mothers Day, May 14th 1967 my father was taking me and my sisters to the Smithsonian Institute [sic] for a traditional Sunday afternoon outing.

I stood out in the middle of the George Washington Memorial Parkway and stopped traffic, I ran in between the two lanes knocking on windows and doors looking for a doctor or someone to help.