Gilberto Alvarado was born in Nicaragua in 1940. He joined the Frente de Liberacion Nacional (FLN) a guerrilla group inspired by the activities of Fidel Castro in Cuba. However, he was also a CIA informant.
In 1963 the FLN sent Alvarado to Mexico in order to obtain entry to Cuba where it was hoped he would be trained in sabotage.
On 25th November, 1963, Alvarado contacted the U.S. embassy in Mexico City and said he had some important information about Lee Harvey Oswald, who had recently been arrested and accused of assassinating John F. Kennedy.
Thomas C. Mann passed the information onto Winston Scott and the following morning, Scott's deputy, Alan White and another CIA officer interviewed Alvarado He claimed that during a visit to the Cuban Embassy he overheard a man he now recognised as Oswald, talking to a red-haired Negro man. According to Alvarado, Oswald said something about being man enough to kill someone. He also claimed that he saw money changing hands. He reported the information at the time to the U.S. Embassy but they replied: "Quit wasting our time. We are working here, not playing."
Winston Scott told David Atlee Phillips about what Alvarado had said to Alan White. On 26th November, Phillips had a meeting with Alvarado in a safe-house. Alvarado told Phillips that the red-haired black man had given Oswald $1,500 for expenses and $5,500 as an advance. Although he was not sure of the date, he thought it was about 18th September.
Mann and David Atlee Phillips believed Alvarado but Winston Scott was not so sure. He argued that there was an "outside possibility" that it might be a set-up by the right-wing government in Nicaragua who wanted the United States to invade Cuba. However, as Jefferson Morley pointed out in Our Man in Mexico: "The unstated message emanating from the White House was by now clear to Win - though not to Mann. Speculation about Oswald's motives was to be cut off, not pursued."
On 27th November, Luis Echeverria told Winston Scott that they had rearrested Silvia Duran because she was trying to leave Mexico for Cuba. Mann sent a message to Scott that stated: "Duran should be told that as the only living non-Cuban who knew the full story, she was in exactly the same position as Oswald prior to the assassination. Her only chance of survival is to come clean with the whole story and cooperate fully. I think she'll crack when confronted with the details."
On 28th November, Winston Scott contacted Luis Echeverria and told him that Washington wanted the Mexicans to interrogate Gilberto Alvarado On 29th November, Scott received a message from John M. Whitten saying: "Please continue to keep us filled in on status of interrogations of Slvia Duran, Alvarado and others implicated as fast as you can get info."
J. Edgar Hoover sent FBI agent, Larry Keenan, to Mexico City in order to have a meeting with Thomas C. Mann, Winston Scott, and David Atlee Phillips. Mann started the meeting by expressing the belief that Fidel Castro and the DGI were behind the assassination of John F. Kennedy and that it was just a matter of time before the United States invaded Cuba. However, Keenan replied that Hoover, Lyndon B. Johnson and Robert Kennedy, all believed that Lee Harvey Oswald acted alone.
Mann later told Dick Russell: "It surprised me so much. That was the only time it ever happened to me - We don't want to hear any more about the case - and tell the Mexican government not to do any more about it, not to do more investigating, we just want to hush it up.... I don't think the U.S. was very forthcoming about Oswald... it was the strangest experience of my life."
In reality, J. Edgar Hoover had not ruled out the possibility of a communist plot to kill John F. Kennedy. At 1.40 on 29th November, Hoover told Lyndon B. Johnson on the telephone: "This angle in Mexico is giving us a great deal of trouble because the story there is of this man Oswald getting $6,500 from the Cuban embassy and then coming back to this country with it. We're not able to prove that fact, but the information was that he was there on the 18th of September in Mexico City and we are able to prove conclusively he was in New Orleans that day. Now then they've changed the dates. The story came in changing the dates to the 28th of September and he was in Mexico City on the 28th. Now the Mexican police have again arrested this woman Duran, who is a member of the Cuban embassy... and we're going to confront her with the original informant, who saw the money pass, so he says, and we're also going to put the lie detector test on him."
That evening Fernando Gutiérrez Barrios told Winston Scott that Gilberto Alvarado had recanted and signed a statement admitting that his story of seeing Lee Harvey Oswald in the Cuban Embassy was completely false. He said his motive was to try to get the United States to take action against Fidel Castro.
A few days later Gilberto Alvarado reverted to his original story. He told his Nicaraguan handler that the only reason that he recanted was that his interrogators threatened "to hang him by his testicles". However, soon afterwards, he recanted again. David Atlee Phillips later claimed that Alvarado was "dispatched to Mexico City by the Somoza brothers... in what they considered a covert action to influence the American government to move against Cuba". Jefferson Morley argues that Phillips is being disingenuous: "Phillips knew all along about Alvarado's service as a CIA informant. Even the FBI knew all along he was under CIA control."
Silvia Duran was questioned about her relationship with Lee Harvey Oswald. Despite being roughed up she denied having a sexual relationship with Oswald. She also claimed that Alvarado was lying about money being passed to Oswald. Luis Echeverria believed her and she was released.