Coleman was a senior attorney on the Warren Commission, entrusted with some of the Commission’s more sensitive work, such as the review of what the CIA and FBI knew about Lee Oswald’s visit to Mexico City.
In his visit to Mexico City in April 1964, he tried and failed to obtain the testimony of Silvia Duran, the receptionist at the Cuban Consulate, who had taken Oswald’s request for a visa to travel to Cuba. Through no fault of his own, Coleman could not get at the truth of the story. He was stonewalled by the CIA and the Mexican government.