We are approaching the half-century anniversary of the assassination of John F. Kennedy, in November 2013, and many serious students of that horrific event still doubt the Warren Commission’s conclusion that Lee Harvey Oswald acted alone. Definitive proof remains elusive, but reasonable speculations abound, and pieces of the puzzle continue to emerge.

The latest, a recent book by a retired CIA analyst, Brian Latell, Castro’s Secrets: The CIA & Cuba’s Intelligence Machine, contains “accounts of how Castro’s spies have carried out political murders, penetrated the U.S. government and generally outwitted their American counterparts,” according to a recent report in The Miami Herald. One dramatic item in the book is that Lee Harvey Oswald warned Cuban intelligence officials of his intention to kill John F. Kennedy “to prove his revolutionary credentials.” Castro knew of this, according to Latell, but did not order or control Oswald’s actions. Castro feared Kennedy was a threat to him and was “probably acting in self-defense.” These disclosures remind students of the assassination of the AP reporter who was warned by Castro shortly before the assassination that the United States’ plans threatening Castro would lead to the endangerment of the U.S. officials. Shortly before the JFK assassination, a CIA official close to the Kennedys was meeting in Paris with a former Cuban official whom the CIA had recruited to kill Castro. These new disclosures add to intelligence gathered in the almost half-century since the assassination of our popular president suggesting — without proving — that Lee Harvey Oswald might not have acted entirely alone.

There is a competing theory about Oswald’s possible allies, also persuasive, also incomplete. Congressional investigations and other analyses of the Mafia suggest — again without proving — that some of its members conspired with Teamster leader Jimmy Hoffa to kill John F. Kennedy. There, too, the dots do not connect. Yet. The Mafia did have a conspiracy to kill JFK, an agreement, means and motive. There is credible evidence from some of them and one’s attorney that they set out to kill JFK. What we do not know is whether the act of Lee Harvey Oswald intervened on, or was a result of, that conspiracy. We cannot connect the dots, though the Mafia acted as if it were responsible, books with reliable sources have reported. Hoffa was rid of his nemesis. Carlos Marcello and others despised RFK’s war against the Mafia. Hoffa rewarded Marcello with a big Teamster loan.

The dots do not connect to prove Oswald acted for the Mafia or as Castro’s pawn. Someday, perhaps when Cuban records are opened, those dots might be connected. They get closer as new disclosures evolve.