The file was one of three obtained by The State. The Columbia, S.C., newspaper filed a Freedom of Information Act request after the South Carolina Republican died in 2003 at the age of 100.
The other files contained information on Thurmond's attempt to get Martin Luther King investigated as a Communist and on threats against him.
The last file detailed an investigation that began when a witness in an unrelated federal case claimed that he had paid Thurmond $20,000 in a Washington restaurant. The witness said he did not known what Thurmond was expected to do in return.
Columnist Jack Anderson printed the allegation, and Thurmond then asked the FBI to investigate. A federal grand jury refused to indict the senator, ending the matter.
"The allegations were very vigorously pursued; no charges were filed because there was no credible evidence whatsoever to sustain them," E. Lawrence Barcella, a former assistant U.S. Attorney who handled the Thurmond investigation, wrote Monday to The State.