The National Archives released another 13,213 records from the Kennedy assassination files on Thursday—mostly unredacted versions of CIA documents that had previously been kept partly classified.
The cache contains documentation of dirty tricks and plots. A CIA report dated April 14, 1967, discusses attempts to kill Cuban dictator Fidel Castro by use of poisoned cigars, targeting his regime with wiretaps and all manner of methods worthy of an espionage novel.
On Nov. 22, 1963—the day President John F. Kennedy was murdered in Dallas—according to the report, a CIA officer in Paris gave "a ballpoint pen rigged as a hypodermic syringe" to a Cuban asset, with the intent to use it as an "assassination weapon" against Castro.
The handoff took place "at the very moment President Kennedy was shot."
"We cannot overemphasize the extent to which responsible Agency officers felt themselves subject to the Kennedy administration's severe pressures to do something about Castro and his regime. The fruitless, and in retrospect, often unrealistic plotting should be viewed in that light," the CIA memo read.
In 1992, Congress set a 25-year deadline for release of all remaining documents related to the assassination. Most of the files were declassified in the 1990s. Oct. 26 was the deadline.
Several agencies lodged last minute objections before last month's deadline, and President Donald Trump agreed that rather than risk irrevocable harm to national security, he would delay release of the disputed files.
He also ordered agencies to swiftly review the records and release as many as possible ahead of a new deadline next April.
The National Archives released 676 documents on Nov. 3, 2,891 documents on Oct. 26, and 3,810 records on July 24.
Researchers have eagerly awaited the files. Many are only tangentially related to the assassination itself. Scholars who've already pored through the sealed material say there are no bombshells, and no evidence to dispute the official finding of the Warren Commission, that Lee Harvey Oswald was the lone gunman and acted alone.
That includes members of the Assassination Records Review Board, the five-member commission created by Congress in 1992 to go through the 5 million records and determine which should remain classified for another 25 years to protect national security, intelligence sources and methods, and diplomatic relations.
But even without evidence to support conspiracy theories, the files are a treasure trove for scholars interested in the FBI's domestic surveillance of civil rights leaders, plots aimed at toppling Fidel Castro in Cuba, and insight into the views of foreign leaders such as Nikita Khrushchev.
Documents released last week show the Soviet leader expressed suspicion that Dallas police must have been involved in the assassination.
The documents also show the pervasiveness of Cold War-era eavesdropping on foreign leaders.