MADISON, Wis. — Newly declassified documents show the FBI kept close tabs on Soviet dictator Josef Stalin's only daughter after her high profile defection to the United States in 1967, gathering details from informants about how her arrival was affecting international relations.

The documents were released Monday to The Associated Press under the Freedom of Information Act following Lana Peters' death last year at age 85 in a Wisconsin nursing home. Her defection to the West during the Cold War embarrassed the ruling communists and made her a best-selling author. And her move was a public relations coup for the U.S.

One April 28, 1967, memo details a conversation with a confidential source who said the defection would have a "profound effect" for anyone else thinking of trying to leave the Soviet Union. The source claimed to have discussed the defection with a Czechoslovak journalist covering the United Nations and a member of the Czechoslovakia "Mission staff."...