ASSOCIATED PRESS WRITER

RICHARD KEIL

WASHINGTON (AP)—The government unlocked 30 years of secrets Monday in John F. Kennedy’s assassination—from CIA theories of Soviet involvement to a second-hand report that Lee Harvey Oswald boasted to a Russian friend ‘‘I will kill the president.’‘

Hundreds of thousands of government documents made public for the first time chronicle the effort by the CIA in the months after Kennedy was killed to determine if there was foreign involvement.

They also detail efforts by the Warren Commission, which investigated the killing, the followup Rockefeller Commission in 1975, the FBI and others to answer persistent questions in the decades that followed.

For instance, 15 years after the assassination an FBI agent interviewed a Russian emigre who recalled nearly verbatim a conversation with a friend, Pavel Golovachev, who had spoken with Oswald in 1962 in Russia.

A former Marine, Oswald defected to the Soviet Union for a period and then returned to the United States before Kennedy was killed.

The Sept. 19, 1977, classified memo to then-FBI Director Clarence Kelley said the emigre’s friend had worked with Oswald at a radio factory in Minsk and had heard Oswald boast ‘‘he would have lots of money in America.’‘

‘‘‘For example, I will kill the president,’‘’ the memo quotes the emigre as saying, recounting Golovachev’s recollection of Oswald’s words.

‘‘Golovachev, who assumed Oswald was joking, also pointed out that he would be arrested and asked what he expected to be paid,’‘ the memo said.

‘‘Oswald responded, ‘You don’t know America. If I manage this, my wife will become rich.’ He said this quietly, but with an angry expression, and sounded serious,‘’ it added.

Many of the newly released documents detailed similar second-hand information or speculation by U.S. intelligence employees trying to make sense of the assassination.

For instance, a Soviet defector working for the CIA speculated in a Nov. 27, 1963 memo that the murder was instigated by the KGB to relieve internal pressures on Nikita Khrushchev, then the leader of the Soviet Union. Khrushchev was deposed in October 1964.

‘‘Our president’s death … effectively diverts the Soviets’ attention from their internal problems. It directly affects Khrushchev’s longevity,‘’ wrote Peter Deryabin, in an eight-page, single-spaced typewritten memo.

Deryabin was a Soviet KGB agent who defected to the West in 1954. He served as a consultant to the U.S. government, including the CIA, and wrote several books. He died about a year ago.

Deryabin’s memo was stamped ‘‘secret’‘ and it offered no factual basis for his speculation that the Soviets were behind Oswald’s shooting of the president in Dallas.

Instead, it listed reasons why Kennedy’s assassination would benefit the Soviets and advanced the idea that the KGB, the Soviet Union’s secret intelligence agency, may have instigated such an act while Oswald lived in the Soviet Union.

‘‘The very real possibility also exists that Oswald was sent here on another mission by the KGB and subsequently accomplished the deed on his own initiative,’‘ Deryabin said.

Other documents detail information the government kept on Oswald before the assassination.

A CIA station officer in Mexico told investigators in one report that Oswald became ‘‘a person of great interest to us’‘ in the fall of 1963 when he went to Mexico City seeking a visa to return to Russia.

‘‘We thought at first that Lee Harvey Oswald might be a dangerous potential defector from the USA to the Soviet Union … so we kept a special watch on him and his activities,’‘ recounted the official, who was not identified in the reported.

The official said, however, the information was not passed along to the FBI.

The National Archives made the documents public as required under a 1992 law.

But historians and JFK enthusiasts may have found as much grist for future discussion and intricate conspiracy theories in the 10,000 CIA documents that remain secret. Also, portions of many of the released documents are blacked out because the information in them is still classified.

Among the documents that are logged but not released:

_A March 6, 1967, three-page memo from then FBI-Director J. Edgar Hoover to Attorney General Nicholas Katzenbach described only as ‘‘Re CIA Mafia connections.’‘

_A May 22, 1961, report in CIA files on ‘‘CIA, Cuba, and Mafia’‘

_Excerpts from the files of then-CIA Director John McCone covering a period from November 1961, through December 1964, that include ‘‘references to Cuba assassinations, Warren Commission matters.’‘