The "thirteenth appendix" to the HSCA Report on the JFK assassination is a staff report entitled "Oswald, the CIA, and Mexico City." This report describes what the Committee learned about Lee Oswald's trip to Mexico City less than two months prior to the assassination. Questions it grapples with include why the CIA was apparently unable to obtain a photo of Oswald from any of its photographic surveillance stations (and instead produced a photo of a "Mystery Man" who was clearly not Oswald), whether Oswald was impersonated in Mexico City, and what credibility to attach to any of the indications and allegations of Communist conspiracy emanating from that city.

The so-called "Lopez Report," written by staffers Dan Hardway and Edwin Lopez, had a number of redactions removed in 2003. These included "CIA A" (Daniel Flores aka Luis Aparacio), "CIA B" (Thomas Keenan), "CIA F" (Robert Zambernardi), LICHANT/1's true name (Manuel Carvillo), and the previously blacked-out crypts ZRSOLO and ZRJOINT. It also revealed the name of a Mexico City CIA Chief of Station, Larry Sternfield. Many redactions remain.

The Lopez Report is a good starting place for grappling with some of the many mysteries of the Mexico City affair. Newly released files have provided new information not present in this report. The LBJ taped phone conversations for instance, include startling corroboration for the claim that audio intercepts of an Oswald impersonator were listened to by FBI agents in Dallas while Oswald was in custody. Declassified testimony of David Phillips, the Tarasoff couple who translated the tapes for the CIA, and others illuminate some areas and deepen the mystery in others.