The untold story of the first U.S.-based nuclear spy, and how he got away with it

The saga of Clarence Hiskey, a chemist employed by the Manhattan Project, and Arthur Adams, a spy-runner, has largely fallen down a memory hole.
MIT Press Reader

This article was originally featured on MIT Press Reader. This article first appeared in the Fall 2023 issue of the Journal of Cold War Studies.

Years before anything was publicly disclosed about the nuclear espionage of Julius and Ethel Rosenberg, Klaus Fuchs, and Theodore Hall, the U.S. Federal Bureau of Investigation (FBI) and U.S. Army Intelligence identified Clarence Hiskey, a Manhattan Project scientist, as a Soviet spy helping to provide highly sensitive nuclear weapons information. The two agencies kept watch on a Soviet intelligence officer, Arthur Adams, who was living illegally in the United States and serving as Hiskey’s control officer. Despite an extensive investigation, neither Hiskey nor Adams was ever arrested. Although Adams was named in a sensational tabloid newspaper article shortly after the end of World War II and closely shadowed by the FBI, he was able to flee to the Soviet Union. Hiskey was never indicted for espionage. Based on material released from declassified Russian archives and FBI files made available under the Freedom of Information Act, the following article tells the story of the first U.S.-based nuclear spy and how he got away with it.

In U.S. popular imagination, Julius Rosenberg and Ethel Rosenberg are usually seen as the most important Soviet nuclear spies. Historians would give that dubious honor to Klaus Fuchs or Theodore Hall. The Rosenbergs and Fuchs were arrested in the early 1950s and convicted of turning over important information about the Manhattan Project to Soviet intelligence agencies. Hall admitted his actions after the Venona decryptions identifying him as a Soviet spy were declassified and made public in 1995. But years before any of their names were public, the U.S. government had discovered another Soviet nuclear spy and removed him from any classified work. His Soviet controller was put under intense surveillance, their machinations were publicly exposed by a tabloid reporter, and congressional hearings gave the U.S. public a glimpse of Soviet efforts to infiltrate the most secret wartime program in the United States. But no one was ever arrested or tried in court. The first government attempt to hold nuclear spies responsible for their actions collapsed several years before the Rosenbergs became the only U.S. citizens to be executed for helping the USSR build its own nuclear bomb.

The saga of Clarence Hiskey, a chemist employed by the Manhattan Project, and Arthur Adams, a Soviet military intelligence officer illegally in the United States, has largely fallen down a memory hole. U.S. Army security officials, the U.S. Federal Bureau of Investigation (FBI), and the U.S. Department of Justice were concerned that arrests would publicize the Manhattan Project before the nuclear bomb was used in combat. They were also leery of disrupting relations with a wartime ally (the USSR) and of mounting a successful prosecution based on covert break-ins and warrantless searches.

Once an anti-Communist reporter for the New York Journal-American broke the story in 1945, shortly after the United States had dropped two bombs on Japan, his combination of factual material and falsehoods ricocheted around the public square, distorting any understanding of what had actually happened. When Hiskey relied on the Fifth Amendment to refuse to testify or answer FBI questions and Adams escaped to the Soviet Union, the case collapsed. After 1991, Russian intelligence agencies continued to follow the Soviet practice of not naming sources who never admitted their spying, and thus even the release of archival records in recent decades has left Adams and Hiskey in obscurity.

The FBI’s reliance on illegal eavesdropping and break-ins thwarted any attempt to bring Hiskey to trial for espionage.

Nonetheless, enough information is now available to tell the story of the first Soviet nuclear spy and the man who recruited him and then successfully evaded the FBI. Some aspects of their actions remain obscure, and the precise nature of the information Hiskey passed to the Soviet Union is unclear, but a great deal of evidence has emerged in recent years about his role as an important spy.

Hiskey was an unlikely candidate for a top-secret government project. Born in 1912 as Clarence Szczechowski in Milwaukee, Wisconsin, to Polish Catholic parents, he had attended La Crosse Teachers’ College before receiving an undergraduate degree from the University of Wisconsin in 1935 and a Ph.D. in chemistry in 1939. Both he and his wife, Marcia Sand Hiskey, were active in Communist organizations on campus. He first came to the attention of the FBI in 1941 in connection with Communist activities at the University of Tennessee, where he was then employed. A former teacher, upon learning that Hiskey was about to be hired by the Tennessee Valley Authority, contacted the FBI to report that, although Hiskey was a brilliant chemist, he was a Communist. A cursory investigation established that Hiskey was widely disliked by his colleagues at Tennessee. One recalled that he was “despicable to inferiors and always trying to impress superiors.” Another said he had a “disgusting personality with a know-it-all attitude.” Later hired at Columbia University to work with Harold Urey, a Nobel Prize–winning chemist, Hiskey experienced a setback in his teaching career when a classroom experiment involving sulfuric acid went awry and caused an explosion.

Army Counter-Intelligence personnel interviewed former professors who described Hiskey as “an out-and-out Red” and outspokenly pro-Soviet and anti-capitalist, but he was still brought to work at the Substitute Alloy Materials Laboratory at Columbia University to take part in sensitive research. At least once, Urey had to caution him to stop discussing his work with unauthorized employees.

Unbeknownst to U.S. investigators, Hiskey was already discussing his classified work with Communist friends connected to Soviet intelligence. In March 1942 he had dinner at his New York apartment with an old comrade from the University of Wisconsin, Zalmond Franklin. Franklin had fought in Spain with the Communist International Brigades and had been recruited to work as a courier by Soviet foreign intelligence officials after his return to the United States. Accompanying him to the subway after dinner, Hiskey swore Franklin to secrecy and then told him that he was working on a powerful radioactive bomb. When Franklin said he certainly hoped that Soviet officials knew about this weapon, Hiskey responded that he “hoped so too.”

When Franklin’s report reached Moscow, it stimulated a sustained but futile effort to recruit Hiskey, complicated by his transfer to Chicago to work at the Manhattan Project’s Metallurgical Laboratory. Ultimately, the recruitment effort failed because, even before his conversation with Franklin, Hiskey was already working for another Soviet intelligence agency, the Main Intelligence Directorate (GRU) of the Red Army’s General Staff.

Hiskey’s GRU contact was Arthur Adams. Several years after being abruptly but quietly removed from the Manhattan Project, Hiskey admitted to the FBI that he had met Adams in the fall of 1941 at a record shop in New York City owned by Eric Bernay. He insisted that the relationship was entirely innocent, claiming that the two had bonded over a shared enthusiasm for left-wing music, such as Spanish Civil War and labor songs. The friendship continued in Chicago, where they supposedly discussed plastics, including Hiskey’s idea of manufacturing a seamless ping-pong ball and Adams’s career in the Soviet Union. Hiskey adamantly denied that Adams ever asked him about his work. Both were lying.

Adams was an important Soviet spy-runner whose long career included several stints in the United States. He lived in several states both legally and illegally, with gainful employment and contrived jobs, as an official of the Soviet government and as an ostensible technical consultant to several U.S. companies. At times his activities were closely monitored by the FBI, but more often he operated totally under its radar.

Several of his U.S. acquaintances had long-standing ties to Soviet intelligence agencies, but the FBI was never able to develop enough evidence to initiate legal prosecutions against any of them. None of the people with whom he had contact were ever successfully prosecuted, even though the FBI found notes on the nuclear bomb during an illegal search of Adams’s hotel room in New York City. He was surveilled for several years by the FBI, but he still managed to flee the country after eluding its agents.

The story of Adams’s connections to Hiskey was a media sensation years before Klaus Fuchs and Julius Rosenberg became household names. Well before several Soviet agents connected to the Rosenbergs eluded the FBI, Adams managed to flee the United States and return to the Soviet Union. He was the first Soviet intelligence officer linked to nuclear espionage and the one about whom the least is known. To this day, his background remains a muddle, with conflicting accounts of his personal history and activities.

Army security officials had belatedly begun to worry that Hiskey was a security risk in 1944, after receiving a tip that he was a Communist. Investigators observed him meeting with a man they later identified as Adams. An illegal entry into Adams’s New York hotel room turned up books on atomic theory and notes indicating that Adams seemed to have knowledge about the Manhattan Project. Concluding that Hiskey was indeed a security risk, the Army sent him a notice that he was being called to active duty (he held a reserve commission).

The day after receiving his call-up, Hiskey met Adams in Chicago and flew to Cleveland after Adams made an airplane reservation for him. During the flight, he engaged in a remarkable conversation with his seat mate, an undercover Army investigator, to whom he declared that capitalism needed to be abolished, that the maldistribution of wealth must be ended, and that “some people will lose their heads to accomplish it.” He spoke warmly about the Soviet Communist system. Once in Ohio, Hiskey met with John Hitchcock Chapin, another chemist working on the Manhattan Project and arranged for him to meet with Adams in the future.

Just a few days later, Hiskey left for his new assignment, a military base in Canada near the Arctic Circle. (The Army later sent him to Hawaii, where he worked on flame-throwing devices.) During the trip, yet another Army investigator obtained access to his luggage and found a notebook with seven pages of top-secret written material, “a concise and comprehensive outline of the DSM Project [initial cover name for the Manhattan Project].” The Army quietly confiscated his luggage, and Hiskey never reported the loss. He wrote to his girlfriend and future wife that, unfortunately, he had been unable to meet as planned with someone in Nome, Alaska, but “things happened which caused him to change his plans,” a hint suggesting to the investigators that he had hoped to rendezvous with another Soviet agent.

Having concluded that Hiskey could be prosecuted or court-martialed for unauthorized possession of classified information (when he left the Metallurgical Laboratory, Hiskey had been instructed to turn in all notes related to the project), the Army was nevertheless reluctant to pursue legal charges for fear of calling attention to the still top-secret Manhattan Project. Satisfied that Hiskey had been neutralized and isolated in the wilds of Canada, Army security decided to turn the investigation of Adams over to the FBI, which put him under surveillance in late August 1944.

Adams, like most Soviet officers, was far from the Hollywood version of a secret agent. About 5 feet, 7 inches tall, weighing 150 pounds, with dark brown eyes, he wore bifocal glasses and was allegedly blind in one eye. His hair was brown, and he was bald on top. Adams wore orthopedic shoes with built-up arches and had an extractable upper plate. He suffered from chronic respiratory illnesses. He dressed conservatively, usually wearing a dark business suit.

Adams had entered the United States from Canada in 1938, falsely swearing that he had never been in the United States before and was planning to open a business. Three days before he arrived in New York, two businessmen, Philip Levy and Jacob Aronoff, opened a bank account for the newly created Technological Laboratories, a company that was to specialize in tool design, with Adams listed as treasurer. Adams later claimed Technological Laboratories employed him through 1943, but, when it was dissolved, a note in its corporate file indicated that it had apparently never done any business, had no inventory, and had never reported any income.

As the FBI dug into Adams’s life, it concluded that he was an “illegal,” that is, a Soviet citizen infiltrated into the United States, operating without diplomatic cover, to direct a group of spies. In 1936 Arthur Ranto, claiming to be Adams’s uncle, had gone before a notary public in Canada and sworn that Adams had been born on 4 May 1890 in Toronto. Thanks to Ranto’s testimony, Adams received a birth certificate and Canadian citizenship. But the Royal Canadian Mounted Police (RCMP) was never able to locate Ranto later or find any records of Adams’s alleged parents. The notary public turned out to be a secret member of the Canadian Communist Party. The records from the town where Adams claimed to have lived from 1909 to 1919 had been destroyed in a fire.

Adams told the local postmaster that he had lost two sons during the war, and he then broke down and sobbed. In fact, he had no children.

Adams told a variety of stories about his birthplace, parents, upbringing, education, and travels. Friends, acquaintances, and business contacts whom the FBI interviewed from 1944 to 1950 offered differing accounts. Adams was sparing with details. According to one relative of his second wife, he would never tell “how long he would be in a place or anything else.” He was also “very cold and unemotional.” He was also a good actor. In 1945, vacationing at a lake in New York State, he told the local postmaster that he had lost two sons during the war, and he then broke down and sobbed. In fact, he had no children. He had abandoned both his first wife and her son (his stepson) and had no contact with them after 1922.

As best the FBI could learn, Adams was actually born in Eskiltuna, Sweden, on October 25th, 1885 to Alexander Adams and Regina Ranto, supposedly an American father (although Adams also later claimed on one visa application that his father was born in Edinburgh, Scotland, and in another that he was of the “Scottish-Finnish race”) and Russian (or Scottish) mother, although no records of his birth could be located. One informant claimed Adams’s father was Swedish and his mother a Russian Jew. In one version of his life story, Adams wrote that he graduated from a naval engineering school in Kronstadt in 1909. A recent Russian account of his background has him brought up in a small village in Russia after his parents died, becoming a revolutionary in 1904, and going into exile after the 1905 Revolution.

Adams entered the United States around 1910 and worked as a tool and die maker in New York in 1917 and 1918. An acquaintance from that time recalled that he “spoke good English” and was thoroughly Americanized. A member of the American Socialist Party, he was appointed head of the technical department of the Martens Mission, the unofficial representative of the new Soviet government to the United States in June 1919. Along with most of the other members of the Martens Mission, Adams returned to the USSR in January 1921 when threatened with deportation.

For the next seven years, Adams lived in the USSR. According to his own account, he variously served as a production engineer and director for the 1st State Auto Works in Moscow, as chief engineer of an aircraft engine department in Leningrad, and as a member of the board of directors of the National Aircraft Industries in Moscow.

Adams returned to the United States in November 1928 for three months as head of a Soviet trade mission attached to Amtorg, the Soviet purchasing company, to buy machinery and plans for the construction of a plant in the Soviet Union to make gas masks. In December 1932, he returned for 10 months as part of a delegation to study and purchase a certain kind of airplane motor at the Curtiss-Wright airplane factory in Paterson, New Jersey. Official delegation documents listed Adams as being in charge of tool design and equipment and indicated he was a Soviet citizen.

Adams was once again in the United States in late 1936 and early 1937, ostensibly to visit relatives of his second wife, Dorothy. Born in Boston in 1898, she had also worked for the Martens Mission and moved to Moscow, where she had worked as a stenographer for high-ranking Soviet officials and as an assistant for the Moscow correspondent of The New York Times. She returned to the Soviet Union in June 1937, but there is no record of when Adams departed. The FBI later speculated that he went to Canada, given that September 1936 was when he showed up in Toronto and falsely claimed Canadian citizenship.

As the FBI dug into Adams’s murky background in 1944 — he had been entirely off its radar until then — it also undertook close surveillance of his movements. But by that point it was too late. A Russian collection of messages on Soviet nuclear espionage, published in 2000, reproduces a letter from Adams, then code-named “Achilles,” to the head of the GRU. Adams had delivered it to Pavel Mikhailov, the acting Soviet consul in New York and the GRU station chief (rezident) in the United States, who presumably shipped it to Moscow via diplomatic courier. Received in Moscow on June 13th, 1944, the letter reported that the United States was working on a bomb using uranium and plutonium (something Soviet officials already knew), headed by six world-famous physicists, including Enrico Fermi and J. Robert Oppenheimer, employing thousands of engineers and technicians, and using three methods of plutonium production at plants in New Mexico and Mississippi (an error). His source was “a highly qualified specialist.” In addition to sending some 1,000 pages of film, Adams included samples of uranium and beryllium. In August, the head of the GRU, General Ivan Il’ichev, sent another 3,869 pages of material received from Adams to Mikhail Pervukhin, one of the main figures overseeing development of the Soviet nuclear bomb.

In late September 1944, FBI agents observed Adams meeting with John Hitchcock Chapin, the Manhattan Project chemist Hiskey had flown to Cleveland to see. They saw something pass between the two men (Chapin later told the FBI it was a key he had given Hiskey as an identifying device). In early October, after Adams had returned to New York, the FBI did a black bag job (gaining surreptitious entry) in Adams’s room at the Peter Cooper Hotel. In a locked briefcase in a locked closet, agents found a sheet of paper with notes containing references to the secret K-25 uranium separation plant at Oak Ridge and “the progress of the experimentation and sources of raw materials” used in the nuclear bomb.

A month later Adams left Aronoff’s New York apartment carrying a heavy suitcase. About 10 PM he entered a car registered to Mikhailov, and the luggage was placed in the trunk. Adams had delivered the final cache of materials he had collected on the nuclear bomb.

A bevy of Adams’s associates and contacts were also closely monitored. Not only Levy and Aronoff but Eric Bernay, one-time publisher of the Communist New Masses and owner of the left-wing music business where he had initially met Hiskey; Samuel Novick, a wealthy businessman who had tried to facilitate Adams’s initial efforts to emigrate from Canada in 1937; Julius Heiman, a long-time conduit for the Soviet jewels that financed the American Communist movement; Irving Lerner, a documentary filmmaker suspected of trying to take unauthorized photographs of the Radiation Laboratory at the University of California; and Victoria Stone, Adams’s mistress and owner of a jewelry store in Manhattan—all were suspected of being part of his apparatus. Most had Communist backgrounds and connections to Soviet intelligence operations.

By January 1945, Adams had become aware of the FBI surveillance, evidently alerted by the break-in at his hotel room. Detecting signs that he was preparing to leave the country, the FBI consulted Manhattan Project security. The Army did not want him to leave the United States because the bomb project was still secret, but also did not want him prosecuted for espionage, for fear that it “would bring the project out into the open.”

On February 25th, 1945, Adams vanished. He had last been seen at 1:30 AM leaving Victoria Stone’s apartment. Appearing to be waiting for a bus, he suddenly jumped into a taxi, and the FBI agent who was trailing him was left stranded when his official car was delayed in arriving. Agents across the country were alerted to be on the lookout for Adams. Train stations and airports were checked, and border offices were instructed to stop him. Worried that he might be en route to the USSR (he had recently purchased a fur coat, collar, and hat), the FBI ordered coverage of all airfields in Alaska used by Soviet aircraft. He was, however, soon spotted on a train to Chicago and, trailed by FBI agents, followed to Portland, Oregon, where, once again concluding that he had been discovered, Adams purchased a ticket to return to New York.

To preclude having to arrest him for espionage, the FBI had filed a sealed complaint charging Adams with violating the Alien Registration laws and making false statements on his Selective Service registration. He was not to be arrested, however, unless he actually tried to leave the country. The charges were thin gruel. Because Adams was 55 years old, the Selective Service charge was unlikely to persuade a jury. Likewise, the Justice Department worried that the immigration charge might run afoul of the statute of limitations. Still, FBI headquarters instructed field agents that under no circumstances should Adams be permitted to board a Soviet vessel of any description, nor should he be permitted to board a Soviet plane. In event such is attempted he should be taken into custody immediately and given a strip search. His luggage should likewise be carefully searched with due regard for rules of evidence.

The spring passed uneventfully. Adams, aware he was being watched, stuck to a boring and predictable routine. But after nuclear bombs were dropped on Hiroshima and Nagasaki in early August 1945, the FBI began to press for action against Adams. The Justice Department showed no sense of urgency, and, before it could decide what to do, its hand was forced. On December 3rd, 1945, Howard Rushmore, a reporter for the New York Journal-American, called two high-ranking FBI officials to tell them that a breaking story on Adams was about to hit the newsstands.

With the headline “Reds Seek Jet Secrets, Spies Bribe US Engineers, FBI Keeps Watch on Atom Agent,” Rushmore’s story published on December 4th, 1945 reported that a Soviet agent was “living under an assumed name at a midtown hotel.” The paper thinly disguised Adams as Alfred Adamson, choosing to keep his real name out of the story. It inaccurately asserted that the FBI had given the State Department “irrefutable proof that Adamson had in his possession secret plans of the atomic bomb given him by an American scientist in Chicago in 1943.” The FBI believed “Adamson passed on atomic bomb information to a Soviet vice-consul a year ago.” Interviewed by a reporter “at an obscure communist musical shop [Bernay’s music store] where he is employed,” Adamson, “visibly nervous,” “denied being a Moscow agent.”

Neither the FBI nor Army investigators ever determined exactly how much nuclear information Hiskey passed to Adams.

Rushmore, a one-time Communist expelled from the party for writing a favorable review in the Daily Worker of “Gone with the Wind,” flogged the Adams story for the next four years, offering a mix of truth spiced with innuendo and wild fantasies. His major source was a disgruntled former FBI special agent, Larry Kerley. An enraged J. Edgar Hoover pushed for the Justice Department to indict Kerley but, by testifying before a House committee, Kerley ensured that any attempt to prosecute him would appear to be an act of petty vindictiveness.

Rushmore’s stories kept the issue of nuclear espionage in the public consciousness, sparking congressional demands for investigations and consequences and intense speculation about how and why no arrests had taken place. The clamor was given an additional dollop of mystery insofar as Rushmore declined to name any of those under suspicion—except for his thinly disguised Adams—for fear of a libel suit. Although reporters knew the identities of everyone mentioned in the articles, the public was treated to stories about “prominent scientists,” “wealthy businessmen,” and “well-connected lawyers.”

The State Department issued truthful denials that it had anything to do with the Adams case, and the FBI remained silent. Out of public view, however, FBI officials conceded that “we have no evidence of espionage activity which can be introduced in court.” There was no proof that the material turned over to Mikhailov, who left the country 10 days after the first Journal-American story appeared, was espionage-related, although it almost certainly was. The most pertinent and damaging physical evidence—a list of questions dealing with the nuclear bomb project—had been obtained through an illegal break-in and could not be introduced into court. Chapin, the one conspirator who later willingly talked to the FBI, had initially claimed that he had not been directly approached to commit espionage. Not until 1946 did he admit that Adams and Hiskey had solicited him to do so. By then, the outstanding indictments against Adams were unlikely to hold up in court.

The blanket surveillance around Adams clearly rattled him, and the FBI hoped he might break down, confess, and ask for asylum. On January 12th, 1946, he had an impromptu and remarkable hour-and-a-half-long conversation with one surveilling agent. Insisting he was a Canadian citizen who wanted to gain U.S. citizenship, Adams denied ever living in the Soviet Union or knowing what the scientists he met in Chicago were working on. He appeared “very nervous and very emotional.” At one point he was “so despondent” that the agent asked whether he had any friends. Adams teared up, saying he had only “that little girl you probably know about,” referring to Stone. He seemed “extremely anxious to talk to someone about his troubles.” The FBI was puzzled by this uncharacteristic behavior and speculated that Adams, knowing that Mikhailov, his GRU superior, had been recalled to Moscow, also feared a recall and was signaling a desire to speak to the FBI. Hoover authorized an interview with him. Approval for the interview came on January 23rd, 1946, the same day that Adams vanished again.

An all-out search failed to turn up any trace of Adams. For months the FBI pursued leads and interviewed his contacts, to no avail. Rushmore broke the story of his flight on February 16th, 1946 with a front-page story, “Atom Spy Eludes FBI as Canada Nabs 22,” referring to the arrests of Canadians implicated by Soviet defector Igor Gouzenko, who had been a GRU code clerk. Because one of those arrested in Canada had the surname Adams, initial reports erroneously stated that Adams had been picked up by the RCMP.

In October 1946, the Justice Department again concluded that the evidence against Hiskey and Chapin was too thin to warrant an indictment. Even so, the clamor around the case continued. Rushmore wrote in the anti-Communist Plain Talk in January 1948 that at least seven unnamed members of Adams’s ring, “the most dangerous spy ring in the history of the United States,” whose members had helped “Stalin’s ace agent attempt to steal the secret of our atom bomb,” were going about their daily lives, “unmolested in the daily pursuit of liberty and happiness.”

The political pressure and growing anger prompted the House Committee on Un-American Activities (HUAC) to hold hearings on nuclear espionage in 1948 during which Kerley testified in executive session that Adams had been allowed to escape by the Truman administration. Rushmore promptly wrote about Kerley’s secret testimony. Hiskey and Chapin testified in public, as did most of Adams’s other American contacts. For the first time, Hiskey’s name became public. He took the Fifth Amendment in response to most questions. Chapin swore that Hiskey and Adams had pressed him to provide nuclear information but that he had refused. In a report issued in October 1948, HUAC recommended that Hiskey, his former wife Marcia, Chapin, and Adams all be prosecuted for conspiracy to commit espionage.7

On October 28th, 1948, Moscow Center sent an encrypted message to a high-ranking Soviet foreign intelligence officer in New York complaining that, even as the U.S. government had embarked on an extensive program to improve its nuclear capabilities, Soviet intelligence efforts had been “unsatisfactory.” Sources who had provided vital information during World War II—“Mlad,” “Caliber,” and “Godsend”—no longer worked at Los Alamos, and the identity of another spy, “Kemp,” had been “completely revealed,” making him useless.

This message was never decrypted and read by U.S. counterintelligence. It was first disclosed in 2009 when the Vassiliev Notebooks (transcriptions of Soviet foreign intelligence documents compiled by Alexander Vassiliev) became available. Whereas Mlad (Theodore Hall), Caliber (David Greenglass), and Godsend (Oscar Seborer) had been publicly identified as Soviet spies in the 1990s, the spy with the cover name “Kemp” had not yet been identified. He was lauded in a book published in 2002 in Russia by Vladimir Lota, who credited Kemp with providing a small container of heavy water and samples of uranium and beryllium, along with thousands of pages of documents from the Manhattan Project to Adams, beginning in 1944. Lota identified “Kemp” as Martin Kemp, a U.S. scientist never previously identified as a Soviet source. Lota claimed that when Kemp failed to show up for a meeting in September 1944, Adams learned he was seriously ill in a hospital and possibly dying. Saying nothing further about “Kemp,” Lota implies by omission that after September 1944 he was dead or no longer involved in the Manhattan Project.

Lota, the nom de plume of retired GRU Colonel Vladimir Ivanovich Boiko, never anticipated that the October 1948 message admitting that “Kemp” had been exposed would ever surface. Like most books written by former Soviet intelligence officers with the approval of their agencies, Lota’s account mixes accurate information with a great deal of disinformation. The only nuclear spy who had dealt extensively with Adams until he was “exposed” in the fall of 1944 was Hiskey.9

In late 1949, after the Soviet test of a nuclear bomb, the Justice Department thought about bringing the case to a federal grand jury, but the FBI was reluctant. For several years, the Justice Department remained interested in filing indictments, but the FBI was still unenthusiastic. Adams was in the USSR. All the principal figures in his ring had either refused to cooperate or denied any knowledge of Adams’s activities. Chapin’s story alone was insufficient to sustain a conviction. He had no evidence but his own recollection, which had changed over time. Although the FBI did not doubt that Adams had been managing Soviet spies since the early 1940s, or that he had solicited the assistance of several people and obtained nuclear information from Hiskey and Chapin, legally admissible evidence to support those charges was thin. Files released by the FBI give no indication that either Hiskey or Chapin was ever observed passing material to Adams. The FBI had never even seen Hiskey and Adams together because that part of the investigation had been conducted by the Army. Material produced during the grand jury proceedings was either classified or based on problematic investigative techniques such as illegal searches. No indictments were issued.

The FBI learned in 1948 from Anna Louise Strong, a prominent pro-Soviet U.S. journalist expelled from the USSR in 1949 on false charges of being a U.S. spy, that Adams was in the Soviet Union. In 1956 a high-level FBI informant in the Communist Party USA reported that Tim Buck, the leader of the Canadian Communist Party, told him that he had recently met with Adams in Moscow. Adams had told Buck a remarkable story of escaping from the United States by climbing through windows, smuggling himself aboard a ship bound for Europe, sneaking into Yugoslavia, and flying to Moscow on a plane provided by the Yugoslav leader Josip Broz Tito. After a lengthy investigation, the FBI concluded that Buck had indeed met with Adams, but that the account of his escape was hogwash. The FBI never learned how Adams eluded surveillance and fled the country.

According to information on a Russian website, Adams worked from 1946 to 1948 for the GRU General Staff but was dismissed in 1948 as the purge of “rootless cosmopolitans” (Stalin’s derogatory term for Jews) gathered steam. For many years, according to the website, he worked as a political writer for the TASS news agency. He died on January 14th, 1969. In 1999 Boris Yeltsin posthumously awarded him the title of Hero of the Russian Federation “for courage and heroism shown during the performance of special assignments.”

Hiskey was called before several congressional committees over the years but persistently pleaded the Fifth Amendment. He had obtained a teaching job at Brooklyn Polytechnic Institute before his name became public. The president of the institute was an anti-Communist, but he rebuffed demands that Hiskey be fired, insisting that only if Hiskey were found guilty would he be let go. Although Hiskey was suspended after being indicted for contempt of Congress, he was reinstated after being acquitted. Nevertheless, he was never promoted, and in 1952 he finally resigned to become an industrial consultant. He later worked for a chemical company and as director of analytical research for Endo Laboratories. He died in 1998.

None of those investigated for ties to Adams ever faced prosecution, although one, Samuel Novick, a wealthy businessman, moved to Mexico in 1951 and remained there for the rest of his life. Hiskey’s most notorious acquaintance turned out to be his son, Nicholas Sand, also a chemist. Sand made headlines in the 1960s not for espionage but for producing the purest commercial version of the psychedelic drug LSD, labeled “Orange Sunshine.” Convicted of drug trafficking and sentenced to 15 years in prison, Sand jumped bail while his case was being appealed and fled to Canada, where he lived under an alias for two decades while producing psilocybin mushrooms and LSD. Arrested by the RCMP with enough LSD “to dose the whole of Canada two times over,” he was imprisoned and eventually deported to the United States. Released from prison in 2001, he remained an unrepentant drug producer until his death in 2017, boasting that he had manufactured enough LSD for nearly 140 million doses.

Neither the FBI nor Army investigators ever determined exactly how much nuclear information Hiskey passed to Adams, although Russian archival documents claim that, beginning in 1944, “Kemp” gave Adams samples of nuclear materials and nearly 4,000 pages of documents. Hiskey apparently cooperated with Adams beginning in 1941, but exactly what information he provided remains unknown. Because Hiskey went to his grave denying he had been a spy, the GRU never credited him. The Soviet practice—still observed by the intelligence services in post-Soviet Russia—was not to reveal the names of spies who had not admitted their activities. Hiskey was one of only two chemists employed by the Manhattan Project who turned over nuclear information to the USSR. Fuchs and Hall were physicists, Greenglass a machinist, and Seborer an engineer. George Koval was a chemist, but his information was mostly about polonium initiators and plutonium production. The classified information provided by Hiskey relating to other chemicals may well have been unique.

Other Russian sources are far from reliable. One website asserts that Hiskey told Adams that his friend “Kemp” had access to classified material and that he photographed what Kemp gave him. But the site also erroneously says that Adams sent more than 5,000 pages of material and samples of plutonium from Los Alamos to Moscow—at times when Hiskey was in Canada, Adams was under suffocating surveillance, and no one fitting Kemp’s description was at Los Alamos.

The FBI obtained records indicating that Adams stayed at the LaSalle Hotel in Chicago at least eight times from December 1942 to September 1943. Hiskey was not assigned to the Metallurgical Laboratory until October 1943, so it is possible that Adams was meeting with someone else connected with the Manhattan Project during this period, perhaps someone suggested by Hiskey. Thus, some of the material Adams sent to Moscow in 1944 might have come from someone other than Hiskey. The 1948 Soviet cable about the source’s public exposure leaves little doubt that “Kemp” was a GRU code name for Hiskey, the only nuclear spy who had been exposed by 1948, and that some of the claims in Lota’s book were nothing more than disinformation.

Clarence Hiskey, lionized as late as 1986 as an innocent victim of government intimidation in a book on the ravages of McCarthyism, paid a small price for turning over a significant amount of top-secret information to Adams, a veteran Soviet intelligence agent who enlisted numerous prominent, well-connected businessmen to assist him in purloining information. Although the damage Adams and his enablers did to U.S. security was likely not as bad as that done by Fuchs and Hall, it no doubt contributed to the ability of the USSR to build and test a nuclear bomb years before U.S. counterintelligence expected it.

Harvey Klehr is a professor of politics and history at Emory University.

John Earl Haynes is senior historian emeritus in the Manuscript Division of the U.S. Library of Congress.

Klehr and Haynes are co-authors of “The Secret World of American Communism” and “Venona: Decoding Soviet Espionage in America,” both published by Yale University Press. This article first appeared in the Fall 2023 issue of the Journal of Cold War Studies.

For full footnotes, see the original publication.