Fedora, Tumbleweed, Department 13 & Lee Harvey Oswald
In 1962, a Kremlin-loyal triple agent “informant” by the name of Aleksei Kulak (J. Edgar Hoover’s shielded-from-CIA FEDORA) at the FBI’s NYC field office told his FBI case officer that Igor Brykin at the UN was an officer of the KGB’s First Chief Directorate’s Department 13 — the KGB’s assassination and sabotage unit.
At the time the FBI and the CIA were running a joint operation against Brykin’s boss at the Soviet embassy in Mexico City, Valery Kostikov.
The FBI / CIA operation involved sending a German national Oklahoma crop-duster and “former” KGB agent by the name of Guenter Heinz Schulz (cryptonym: TUMBLEWEED) to meet with Kostikov about an operation in the US that he and Brykin were to collaborate on.
On 1 October 1963 Lee Harvey Oswald, or someone impersonating him, called the Soviet consulate in Mexico City. The phone was answered by Ivan Obyedkov, the embassy’s security officer whom the CIA mistakenly believed it had successfully recruited.
Oswald or “Oswald” said he had met with a Soviet diplomat at the consulate a few days earlier about getting a visa to the USSR but couldn’t remember his name.
Obyedkov volunteered, “Kostikov. He is dark.”
Oswald said, “Yes.”
The phone call was tapped by the CIA, and after the assassination of JFK seven weeks later, the Agency and the FBI were mortified to learn that his assassin had been in touch with the putative* head of KGB assassinations for the Western Hemisphere.
Whether or not the Soviets had had anything to do with the assassination, this made it imperative for the FBI and the Warren Commission to find they hadn’t.
*Official CIA historian David Robarge has said it was never proved one way or the other if Kostikov was Department 13.