Klaus Fuchs

Refugee and scientist

He was born on 29 December 1911 in Rüsselsheim and studied, among other places, in Leipzig. He received a PhD in physics from Bristol and a Doctor of Science degree from Edinburgh.³

In the early 1930s he was an anti-Nazi activist and a communist in Germany. In 1933 he fled to Britain. After the outbreak of war he was interned on the Isle of Man and then sent to Canada.^1,2

The atomic bomb

In 1941 he returned to Edinburgh and, recruited by Rudolf Peierls, began working on Britain’s nuclear weapons programme, Tube Alloys. He was already passing information to the Soviet Union.^1,3

In 1943 he went to the United States with the British team, and in August 1944 he moved to Los Alamos, to the Theoretical Physics Division led by Hans Bethe. He passed detailed information on atomic weapons design to his Soviet handlers, meeting a courier in Santa Fe.^1,3,4

In 1946 he returned to Britain and took up a post at the Atomic Energy Research Establishment at Harwell in Oxfordshire.¹

Detection and trial

He was exposed largely by decrypted Venona messages, including some about his meetings with the courier Harry Gold. By 1949 the suspects had been narrowed down to him and Rudolf Peierls.^1,4

William ‘Jim’ Skardon of MI5, a former Special Branch officer, spent several months gaining his trust and confronted him in December 1949. In January 1950 Fuchs confessed everything; his handwritten confession from prison, dated February 1950, is in file KV 2/1252.^1,4,5

Arrested in February 1950, he pleaded guilty in a short trial to breaching the Official Secrets Act and in March 1950 received the maximum sentence of 14 years’ imprisonment. His confession led the FBI to Harry Gold and, through him, to David Greenglass.^1,3,4

In East Germany

He was released after nine years and moved to East Germany, where he became a prominent physicist and scientific leader. He died on 28 January 1988 in East Berlin.^1,3

The US Department of Energy counts him among the most valuable Soviet spies not caught during the war. It also judges that Soviet espionage against the Manhattan Project probably hastened the Soviet acquisition of an atomic bomb by at least 12–18 months.⁴