During the Second World War, Sikorski took command of the Polish army in France and thereafter became the head of the Polish government in exile. At the time of his death, on July 4th 1943, he was returning to London from the Middle East where he had been inspecting Polish troops which were about to join the allies. He was notably accompanied by two British MPs, his chief of staff and his daughter. His plane crashed into the sea just a few seconds after take-off from Gibraltar, allegedly due to a technical failure. Apart from the Czech pilot, all the passengers on board were killed. British investigations in the aftermath of his death concluded that it was an accident.
New investigations in 1992 revealed, however, that, at the height and speed at which it was travelling, the plane could technically not have crashed. Some claimed that the pilot had deliberately brought the plane down. The mystery of Sikorski’s death remains and has since been subject to various theories: a murder planned by the Soviet Union or by the British government.
Ewa Koj, the prosecutor overseeing the investigation claimed that: