The U.S. Department of Energy has declassified documents related to a Cold War hearing for the man who directed the Manhattan Project and was later accused of having communist sympathies.

The department last week released transcripts of the 1950s hearings on the security clearance of J. Robert Oppenheimer, providing more insight into the previously secret world that surrounded development of the .

Oppenheimer led the Manhattan Project at Los Alamos National Laboratory, which developed the atomic bombs dropped on Hiroshima and Nagasaki during World War II.

Oppenheimer later lost his security clearance following hearings on his alleged connection to leftist causes.

The department previously declassified portions of the transcripts but with redacted information.