In an operation lasting around eight hours, pathologists removed the body of Wladyslaw Sikorski from its two-ton marble sarcophagus in the crypt of Krakow's Wawel Cathedral, the resting place of many of Poland's national heroes.

The general's coffin was then taken to a laboratory to undergo tests as part of a criminal investigation to determine whether General Sikorski, who was prime minister of Poland's government in exile and commander of its armed forces, was murdered or died when his RAF Liberator crashed into the sea seconds after taking off from Gibraltar in July 1943.

Prosecutors from Poland's Institute of National Remembrance, the body charged with investigating Poland's wartime and communist past, are especially keen to examine the skull to see if the general was shot dead before the aircraft plunged into the sea, killing all on board except the Czech pilot.

Although a British inquiry attributed the crash to a technical malfunction, speculation has abounded that the general was assassinated, with various conspiracy theories accusing Stalin, Churchill or even fellow Poles of his murder.