Sylvia Ageloff and the assassination of Leon Trotsky on February 6. On August 20, 1940, Leon Trotsky was assassinated by Stalinist agent Ramón Mercader in the Mexico City suburb of Coyoacán. Mercader’s access to the great revolutionary was made possible through his relationship with Sylvia Ageloff, a member of the Socialist Workers Party (SWP). In the aftermath of the assassination, Ageloff presented herself as an innocent victim of Mercader’s duplicity, a claim that was never challenged by the SWP. This series of articles constitutes the first systematic investigation by the Trotskyist movement of Ageloff’s role and continues the work of the International Committee of the Fourth International’s Security and the Fourth International investigation. It is published in four parts.