My response to the Quora question, “A CIA document released in 1977 reports French government officials asking the FBI why a rogue French captain and OAS operative was being deported from Texas shortly after the JFK assassination. What do we know about him? Why was he deported?”
I assume you are referring to Jean Rene Marie Souetre, and not Lucien Sarti or SDECE officer Michel Victor Mertz, both of whom were French Corsican mobsters and heroin traffickers.
Robert Morrow, who claims he worked under contract for CIA, says there were at least two teams of assassins in Dealey Plaza on November 22, 1963, one of which was led by a French gunman he knew as “John Michael Mertz.” Morrow also claims David Ferrie planned the assassination and that Clay Shaw was involved.
Morrow says he purchased three rifles used in the shooting from Sunny’s Surplus in Baltimore. The rifles were given to Mertz’s team, which included Souetre.
Researcher Gary Shaw says CIA records indicate that Souetre was in Dallas on November 22nd, and was expelled from the country the next day. The FBI says that it was another Frenchman named Michel Roux, who had been deported. However, Souetre often used the name “Roux” as an alias, as investigative author Anthony Summers wrote in “Conspiracy.”[3,4] Roux, by the way, is also a real person.
Researchers Lamar Waldron and Thom Hartmann, assembling information from Senate investigator Bud Fensterwald, Pulitzer-Prize winner William Attwood, and French journalist Stephane Risset, who interviewed Souetre, claim an assassination team consisting of Johnny Roselli (yes, the Mafia figure), Jose Marie Andre Mankel (CIA cryptonym QJWIN), and Souetre were in Dallas that day.
A CIA memo says that SOUTRE (aka MERTZ) was “expelled from the US… 48 hours after the assassination of President Kennedy.” In 1983, Souetre said that the Frenchman in Dallas was in fact Mertz, using Souetre’s name.
In “The Man Who Knew Too Much,” author Dick Russell writes about Richard Case Nagell, who says he was a double agent given a mission, perhaps by the KGB, to stop Lee Harvey Oswald. Russell describes Nagell’s operating world as one of shifting identities. He also writes about the Souetre-Roux-Mertz connection, noting Mertz’s role in the Corsican mafia.
Postscript: Former FBI agent Donald Adams mapped out where the shots came from. There were 11 shots in all, five hits. Three of those came from the rear, one non-fatal shot into President John Kennedy’s back, and two into Texas Governor John Connolly, one in his back and one in his wrist.
Two or possibly three venues in the rear were used—the sixth floor of the Texas Book Depository, with a sightline obscured by trees, and the much clearer view from the roofs of the Dal-Tex Building and the Dallas County Records Building.
Two shots hit from the grassy knoll in front as the president’s motorcade approached, one into the throat of JFK and the lethal shot to Kennedy’s head. There were at least six shots that missed, coming from the Dal-Tex Building, the grassy knoll and the Triple Underpass.
Soutre (“Mertz”) was nabbed by law enforcement almost immediately, but was released two days later when Assistant Attorney General Nicholas Katzenbach told the INS that Dallas police had the assassin, Lee Harvey Oswald. Soutre was then flown to Montreal.
 Conspiracy, by Anthony Summers, McGraw-Hill, 1980
 Not in Your Lifetime: The Defining Book on the J.F.K. Assassination, by Anthony Summers, Open Road, 1998
 Copy of QJWIN’s
 Declassified CIA memo: