After the first few years in prison, Ramon Mercader requested to be released on parole, but the request was denied by the Mexican authorities. They were represented by Jesús Siordia and the criminologist Alfonso Quiroz Cuarón. In 1943 Caridad Mercader applied to Stalin personally for her part in the secret operation to release Ramon Mercader. In 1944 she obtained a permit to leave the USSR. However, contrary to the agreed upon conditions, she not only led the attempt of release of Ramon at a distance, but traveled to Mexico, where she was known if not as the mother of Ramon, but as the organizer of the assassination. That undermined an undercover operation that was being prepared to get Ramón Mercader out of jail. Caridad Mercader's presence proved to be counterproductive, because she improved the life of Ramon in prison most significantly but the Mexican authorities tightened security measures, causing the Soviets to abandon their efforts to release Ramon. Though Caridad reported very important things to the Mexican authorities, Ramon served 20 years and 1 day in prison (including the time under initial investigation and trial) according to the initial trial. Ramón, who according to his brother Luis never shared his mother's passion for the communist cause, never forgave her this interference.