Boris Pash

Boris Pash was a United States Army counterintelligence officer whose suspicion of the Soviet Union turned a fragmentary wartime intelligence lead into an expansive investigation of scientists associated with the atomic-bomb project. As Manhattan Project counterintelligence chief, he pursued possible espionage at the Berkeley radiation laboratory, treated J. Robert Oppenheimer’s political associations as grounds for alarm, and sought to expose what he believed was a Soviet network. His methods could be extreme, but his investigation also produced a recorded interview whose unresolved contradictions would later become a liability for Oppenheimer.

Identity and Background

A native of San Francisco, Pash had formed his hostility to revolutionary communism through direct experience. During World War I, he accompanied his Russian Orthodox bishop father to Moscow. When the Bolsheviks seized power, Pash joined the counterrevolutionary White Army and fought in the civil war of 1918–20. He later returned to the United States after marrying a Russian aristocrat. The account presents that early history not as incidental biography but as a foundation for his enduring view of the Soviet Union: he regarded it as a mortal enemy, not merely a wartime ally.

During the 1920s and 1930s, Pash worked as a high-school football coach while serving in summers as a reserve United States Army intelligence officer. After the United States entered the war, he assisted in the internment of Japanese Americans on the West Coast. He was then assigned as chief counterintelligence officer for the Manhattan Project, a position that placed him between the military’s secrecy requirements and a scientific community whose political associations included people he regarded as potential security threats.

Descriptions of Pash diverged sharply. Admirers called him “cunning and shrewd”; others dismissed him as a “crazy Russian.” He had little patience for bureaucratic delay and thought of himself as a man of action. That combination of ideological certainty and impatience mattered in the investigation: he was inclined to treat ambiguous information as a lead demanding immediate intervention, rather than as uncertainty requiring restraint.

From a Wiretap to a Suspected Network

An FBI transcript of a conversation between Steve Nelson and an unidentified man known as “Joe” was delivered to Pash at Army intelligence in San Francisco. The conversation concerned technical information that might help the Soviet Union, then an American wartime ally. Pash quickly concluded that it indicated espionage and confirmed his existing suspicions about Oppenheimer. Because the wiretap had been illegal, authorities could not use it to prosecute Nelson or the unidentified speaker. Pash was nevertheless authorized to investigate whether the Berkeley laboratory had been targeted, using the information to trace Nelson’s contacts.

Pash’s investigators initially focused on Giovanni Rossi Lomanitz because Pash had information that Lomanitz belonged to the Communist Party. They followed him and watched him pose for a campus photographer with friends outside Sather Gate at the University of California, Berkeley. After the group dispersed, an agent bought the photographic negative. The friends were identified as Joseph Weinberg, David Bohm, and Max Friedman, all students of Oppenheimer. The image, an ordinary group photograph, became a means of identifying and marking the four young men as subversives in the investigation.

Pash later claimed that investigators had established the four men’s frequent association and identified “Joe” as Weinberg. He also said he had sufficient information to identify Weinberg and Bohm as Communist Party members. Those assertions formed part of his belief that he had uncovered a sophisticated Soviet network. The evidence described in the account, however, shows how quickly association and political suspicion became intertwined in the inquiry: the photographed friendships helped direct surveillance, while the surveillance was interpreted through Pash’s prior conviction that espionage was taking place.

Escalation and the Oppenheimer Inquiry

In July 1943, Pash wanted to take Lomanitz, Weinberg, Bohm, and Friedman out to sea and interrogate them “after the Russian manner.” The FBI reported that information obtained in such a way could not be used in court and feared that Pash did not intend to leave anyone available for prosecution. The Bureau applied pressure to stop the plan. The episode shows the practical consequence of Pash’s preference for action: in his effort to break suspects, he proposed a method that other investigators regarded as beyond the bounds of a usable legal inquiry.

Pash also suspected that Oppenheimer might be passing information to the Communist Party through his contacts, even if he was not doing so directly. On June 29, 1943, he recommended that Oppenheimer be denied a security clearance and fired, citing circumstantial evidence that included Oppenheimer’s visit to Jean Tatlock and a telephone call to David Hawkins. Pash considered Tatlock a possible conduit and hoped surveillance of her telephone would confirm his theory. When proof seemed uncertain, he intended to use Oppenheimer’s relationship with her as leverage. In a memorandum to John Lansdale, Pash recommended that Oppenheimer be summoned to Washington and threatened with the Espionage Act if he could not simply be dismissed. He believed Oppenheimer’s ambition and concern for his reputation could be used to secure his cooperation.

Oppenheimer’s own warning about George C. Eltenton brought the investigation into a direct encounter. After Oppenheimer told an Army security officer that Eltenton might be trying to obtain information from the radiation laboratory, Pash ordered him to return for an interview. A microphone had been hidden in the officer’s telephone, with a recording device in an adjoining room. When Oppenheimer arrived, he was startled to find Pash there; Pash conducted the interrogation himself.

In that interview, Oppenheimer identified Eltenton as a possible source of an espionage approach but described the intermediary and other scientists involved as innocent without naming them. He insisted that matters at Los Alamos were “100 percent in order” and said he would be willing to be shot if he had done anything wrong. The performance, as the account characterizes it, was both strange and consequential: Oppenheimer spoke with confidence about his judgments while withholding names that Pash wanted to know.

The recording became part of Oppenheimer’s security file. Oppenheimer later said that his account of the approaches—whether there had been two or three was unclear—was an inaccurate “cock and bull” story whose origins he could not explain. As a result, the recording left a lasting ambiguity: it could not establish whether he had lied to Pash at the time or had told the truth and lied later. The interview thus outlasted the immediate investigation, becoming a delayed problem in Oppenheimer’s security history.

Investigation, Transfer, and Later Reputation

Pash spent two frustrating months in the autumn of 1943 trying to discover who had approached Oppenheimer about passing information to the Soviet consulate. His agents repeatedly interviewed Berkeley students and faculty members, but the investigation did not identify the contact. His hostility toward Oppenheimer and his continuing pursuit of the case led Leslie Groves to conclude that Pash was wasting Army time and resources on an inquiry that was going nowhere. In early December, Groves ordered Oppenheimer to name the contact: Haakon Chevalier.

Pash had already been moved toward another assignment. In November 1943, he was made military commander of Alsos, a secret mission intended to determine the status of the Nazi bomb program by capturing German scientists. He went to London to prepare a team of scientists and soldiers to follow Allied forces into Europe. After the war, he was decorated for his leadership of Alsos; its raiding teams seized dozens of German scientists and 70,000 tons of Axis uranium ore in 1944 and 1945. His career therefore included both a stalled domestic counterintelligence investigation and a secret overseas operation that achieved substantial material and intelligence gains.

Pash’s attention to Tatlock did not produce confirmation that she had served as a conduit for information to the Soviet Union. The surveillance continued after his departure, but the agents learned nothing to substantiate the suspicion. Years later, her brother and other investigators questioned the conclusion that her death was suicide, particularly after the United States Senate’s Church Committee hearings made information about intelligence-agency assassination plots public. That renewed suspicion arose in part from Pash’s later record, not from proof that he had harmed Tatlock. From 1949 to 1952, he headed Program Branch 7, a special-operations unit within the CIA’s Office of Policy Coordination. His superior told Senate investigators that the unit was responsible for assassinations and kidnappings; Pash denied being delegated responsibility for assassinations, while acknowledging that others in the agency could reasonably have gained that impression.

Character and Narrative Significance

Pash’s role in Oppenheimer’s story rests on a consequential mismatch between certainty and proof. He saw political connections as signs of a possible espionage apparatus, and the illegal wiretap that supplied his initial lead could not itself support prosecution. His suspicions nevertheless shaped surveillance, personnel recommendations, and an interrogation conducted under secret recording. The investigation did not establish the network he believed he had found, but it helped create a documentary record that later made Oppenheimer’s own shifting account difficult to resolve.

The portrait does not reduce Pash to a single episode. His military and intelligence career continued beyond the Berkeley inquiry, and his command of Alsos brought him formal recognition. Yet the same impatience and belief in decisive action that informed his wartime counterintelligence work also produced the proposed abduction of four scientists and an investigation that Groves judged unproductive. Pash’s significance lies in that tension: he was an effective operator in one secret mission and a forceful, often alarming investigator in another, while the records he helped generate continued to shape the story long after his immediate pursuit had ended.