Rudolph Carl Lambert was an American citizen and head of the California Communist Party

Communist party

A political party described as a Communist party includes those that advocate the application of the social principles of communism through a communist form of government...

 Labor Commission and also headed of its security section in the 1940s. Lambert first fell under FBI scrutiny in connection with its Comintern Apparatus investigation. Lambert is named in a 1945 San Francisco KGB

KGB

The KGB was the commonly used acronym for the . It was the national security agency of the Soviet Union from 1954 until 1991, and was the premier internal security, intelligence, and secret police organization during that time.The State Security Agency of the Republic of Belarus currently uses the...

 cable intercepted and deciphered by the Venona project

Venona project

The VENONA project was a long-running secret collaboration of the United States and United Kingdom intelligence agencies involving cryptanalysis of messages sent by intelligence agencies of the Soviet Union, the majority during World War II...

 discussing information about uranium deposits in Western states.

Lambert figured prominently in the U.S. Atomic Energy Commission

United States Atomic Energy Commission

The United States Atomic Energy Commission was an agency of the United States government established after World War II by Congress to foster and control the peace time development of atomic science and technology. President Harry S...

's investigation and decision to relieve Dr. J. Robert Oppenheimer, Director of the Manhattan Project

Manhattan Project

The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...

 at Los Alamos

Los Alamos National Laboratory

Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

, of his security clearance

Security clearance

A security clearance is a status granted to individuals allowing them access to classified information, i.e., state secrets, or to restricted areas after completion of a thorough background check. The term "security clearance" is also sometimes used in private organizations that have a formal...

 because of documented close associations which Oppenheimer repeatedly denied, yet ultimately admitted to. In a subsection review 'As to "character"' on 29 June 1954 in the Decision in the Matter of Dr. J. Robert Oppenheimer, the Commission wrote,

"(3) In 1943, Dr. Oppenheimer indicated to Colonel Lansdale that he did not know Rudy Lambert, a Communist Party functionary. In fact, Dr. Oppenheimer asked Colonel Lansdale what Lambert looked like. Now, however, Dr. Oppenheimer under oath has admitted that be knew and had seen Lambert at least half a dozen times prior to 1943; he supplied a detailed description of Lambert; he said that once or twice he had lunch with Lambert and Isaac Folkoff

Isaac Folkoff

Isaac "Pop" Folkoff was a senior founding member of the California Communist Party and West Coast liaison between Soviet intelligence and the Communist Party USA . Folkoff was in charge of West Coast operations. Folkoff worked as a courier passing information to and from Soviet sources, and as a...

, another Communist Party functionary, to discuss his (Oppenheimer's) contributions to the Communist Party; and that he knew at the time that Lambert was an official in the Communist Party (Tr. pp. 139, 140, 877)."