Newly-released uncensored FBI files on Marilyn Monroe reveal the names of suspected communist friends, who drew concern from government officials and her own entourage.
But the documents, which previously were heavily redacted, do not contain any new information about the film star's death 50 years ago.
The files were obtained by The Associated Press through the Freedom of Information Act.
They show the extent to which US spies monitored Monroe between 1955 and August 1962 when she died.
But the FBI never found any proof she was a member of the Communist Party.
One entry, which previously had been almost completely redacted, concerned intelligence that she and other entertainers sought visas to visit Russia.
They also reveal that some in the star's inner circle were concerned about her association with Frederick Vanderbilt Field, who was disinherited from his wealthy family over his left-wing views.
A trip to Mexico in 1962 to shop for furniture brought her in contact with Mr Field, who was living in the country with his wife in self-imposed exile.
Informants reported to the FBI that a "mutual infatuation" had developed between the pair, which caused concern among some in her inner circle, including her therapist, the files say.
Under J Edgar Hoover's watch, the FBI kept watch on the political and social lives of many celebrities, including Frank Sinatra, Charlie Chaplin and Monroe's ex-husband Arthur Miller.
For years, the FBI files on Monroe have intrigued investigators, biographers and those who refuse to believe her death at her Los Angeles area home was a suicide.
Norman Mailer's famous biography of the actress focused on theories that she was killed by the government.
A 1982 investigation by the Los Angeles District Attorney's Office found no evidence of foul play after reviewing all available investigative records, but it stated at that time that the FBI files were "heavily censored".