The memo is one of many included in Miller's FBI files, obtained by The Associated Press through the Freedom of Information Act. Miller, who died last year at age 89, was a longtime liberal who opposed the Vietnam War, supported civil rights and, in one play, "The Crucible," linked the Cold War pursuit of communists to the Salem witch trials of the 17th century.
His files only became available after his death, but the government's interest in Miller was well established in his lifetime. In 1956, the House Un-American Activities Committee asked him to give names of alleged communist writers with whom he had attended some meetings in the 1940s. Miller refused and was convicted of contempt of Congress, a decision eventually overturned by the U.S. Supreme Court.
For a decade before his congressional testimony, the FBI kept track of the playwright, but ended up making a more convincing case that Miller was a dissenter from the Communist Party rather than a sympathizer, the AP reports.
According to a 34-page FBI report, compiled in 1951, Miller was identified by an informant as being "under Communist Party discipline" in the 1930s and, as of the mid-1940s, a member.