Washington ? After fighting to keep them secret for more than three decades, the CIA released hundreds of documents Tuesday that catalog some of the most egregious intelligence abuses of the Cold War, including assassination plots against foreign leaders and illegal efforts to spy on Americans.

Fidel Castro exhales cigar smoke in this March 1985 file photo during an interview in Havana. Newly declassified CIA papers released Tuesday detail a plot to have American mobsters try to kill the Cuban leader in the early 1960s.

The records are part of a trove of jealously guarded documents long known within the agency as “the family jewels.” Assembled in the early 1970s as part of an internal investigation of potentially embarrassing or illegal activities, the records were subsequently turned over to Congress, prompting multiple investigations and sweeping intelligence reforms.

The records were ordered released by CIA Director Michael Hayden as part of what he characterized as an effort to close an embarrassing chapter in the agency’s history.

The documents serve as “reminders of some things the CIA should not have done,” Hayden said in remarks to the agency’s work force Tuesday. “The documents truly do provide a glimpse of a very different era and a very different agency.”

Indeed, many of the episodes detailed in the 693 pages of newly declassified text read like relics from another era, including the elaborate attempts by the CIA to enlist mafia operatives to poison Cuban leader Fidel Castro.

But other documents seem remarkably relevant today, as the nation grapples anew with questions of how much latitude U.S. intelligence agencies should be given in the wake of the Sept. 11 attacks.

The documents describe secret CIA holding cells and the possibly illegal detention of a suspected Soviet spy who was held without trial at a CIA facility in Maryland for years before it was determined he was a legitimate defector. They also document plans to eavesdrop on international phone calls of U.S. residents, and aggressive efforts to root out leaks of classified information to reporters.

Voluntary release

Watchdog groups praised the release of the records, and said it was a remarkable step for a secretive organization under no legal obligation to declassify the documents.

“It allows the agency to simultaneously distance itself from its questionable past and portray itself as open and forthcoming,” said Steven Aftergood, director of the project on government secrecy for the Federation of American Scientists.

Even so, the records that were released are incomplete, with dozens of pages blacked out by CIA censors. One memo that lists the most damaging secrets contained in “the family jewels” is missing the first paragraph. A separate memo that is supposed to summarize the “unusual activities” of the CIA’s domestic branch includes just three intact paragraphs followed by 17 blank pages.

The records that are complete do not appear to contain major revelations of CIA misdeeds, but instead provide extensive new detail from internal CIA accounts on episodes that have occupied Cold War historians for decades. Most of the records are memos written by agency officials in response to a 1973 order from then-CIA Director James Schlesinger for employees to report activities they thought might violate the CIA’s charter.

Arguably the most exceptional operation detailed was a plot to enlist known organized-crime figures to assassinate Castro in the early 1960s. Although the machinations were uncovered more than 35 years ago, the newly released reports show that the CIA director at the time, Allen W. Dulles, “was briefed and gave his approval” to the operation.

According to a five-page memo, a private investigator contracted by the CIA worked directly with Chicago crime boss Sam Giancana to come up with the assassination plan. In an almost comical aside, the CIA realized it was dealing with Giancana after subsequently seeing his photo in a most-wanted listing in Parade magazine.

“Sam suggested that they not resort to firearms but, if he could be furnished some type of potent pill, that could be placed in Castro’s food or drink, it would be a much more effective operation,” the memo said.

But after several failed attempts, the Cuban operative selected by the mafia to carry out the assassination “got cold feet and asked out of the assignment.” The mafia suggested another candidate, but the operation was canceled when the botched Bay of Pigs invasion exposed the Kennedy administration to criticism for its anti-Castro policies.

Other enemies

The records also shed extensive light on the CIA’s involvement in efforts to spy on Americans, including student anti-war activists, Black Power group leaders, pro-Castro sympathizers and Soviet dissidents.

Anti-war activists were followed – some all the way to Paris, where they attended summit meetings with Viet Cong representatives. The surveillance turned up financial connections between John Lennon of The Beatles, described only as “a British subject,” and a project linked to anti-war activist Rennie Davis, one of the Chicago Seven.

In a program code-named MHCHAOS, the CIA recruited, tested and dispatched Americans with “existing extremist credentials” abroad so they could gather intelligence on efforts by Cuba, China, North Vietnam, the Soviet Union, North Korea and “the Arab fedayeen” to foment domestic extremism in the United States.

As part of an effort to combat drug trafficking, the CIA asked the U.S. Department of Agriculture to plant a field of opium poppies in Washington state to be used to test “photo-recognition systems” designed to detect illicit crops from overhead.

But the agency refused a request from federal “Alcohol & Tobacco” authorities to use infrared scanners to locate moonshine stills.

A document from 1973 mentions the existence of a 1963 account of agency scientists administering mind- or personality-altering drugs on “unwitting subjects” – that is, testing hallucinogens such as LSD on people without their knowledge. The document doesn’t provide details.