I did not know there had been a Mexican literary connection to the Kennedy assassination but look:
One reason the Alvarado story could be endorsed vigorously by CIA Station Chief Scott was that it was corroborated in small details by other Phase-One stories, also from intelligence sources, and later similarly retracted. One of these corroborative stories was directly attributed to “a CIA man in Dallas,” who allegedly told reporter Jerry O’Leary that Oswald returned from Mexico “with $5,000 which he did not have when he went into Mexico.” O’Leary telephoned this information to FBI Headquarters. The FBI account of this event commented, “In other words, the CIA man in Dallas leaked information to O’Leary.” However a CIA cable the next day reported from Mexico the rumor that Oswald had deposited $5000 in the United States after he got back from Mexico, and attributed the story to “an ODENVY [FBI] man named Clark.”
No Phase-One allegation corroborated Alvarado more closely than that of the well-known right-wing Mexican writer Elena Garro de Paz. She claimed she had been present at a party where she had heard a Communist discussion of Kennedy, in which “they came to the conclusion that the only solution was to kill him.” She had also seen Oswald with the same people at a party given by Rubén Durán, the brother-in-law of Silvia Durán, “who she later learned was Oswald’s mistress while he was here.” In accounts given to the American Embassy in 1965, she linked Oswald to the same striking companions as did Alvarado: “a Latin American Negro man with red hair” and someone with “long blond hair.”
When I wrote about the Garro allegations in 1993, I discounted them, on the grounds that Alvarado’s story of a “Negro with reddish hair” had already been published in September 1964 in the Warren Report. I now think it much more likely that some version of the Garro story had reached the DFS, or been planted by them, in the days following the assassination. No one disputes Garro’s story that the DFS took her into protective custody between November 23 and November 30. Her story would explain why on the same day the DFS arrested, not only Silvia, but her husband Horacio, sister-in-law Lydia Durán, and brother-in-law Rubén Durán and his wife Betty (all placed by Garro in Oswald’s presence at the incriminating party). It would also explain why, on November 23, the DFS was grilling Silvia so aggressively about her sexual affair and Communist plotting with Oswald. Finally it would explain why Silvia on November 23 attributed her arrest to her cousin [i.e. Garro] whom she “does not like.”
The management of the Garro story was different from those of Silvia Durán and Alvarado. It was a Phase-One story from start to finish; as it never reached Washington through the usual CIA channels, so there was no need to reshape or retract it. The management consisted of keeping her in DFS custody, at a time when FBI personnel should have been interviewing her.
I do not really know what Peter Dale Scott has figured out about the Kennedy assassination but this quotation is from this piece.