By Adam Easton
BBC News, Warsaw
Sikorski's marble tomb lies near those of monarchs and national heroes
Prosecutors in Poland have exhumed the body of the country's World War II prime minister in an attempt to solve the mystery as to how he died.
General Wladyslaw Sikorski died in a plane crash in Gibraltar in 1943.
A British investigation ruled that it was an accident, but some historians in Poland believe Gen Sikorski died as a result of foul play.
Prosecutors say they are investigating a communist crime. Poland's president and PM are backing the current inquiry.
A small team of prosecutors, scientists and church officials took part in the opening of the general's marble tomb in Krakow cathedral, where it lay next to Polish monarchs and national heroes.
The general's coffin will now be taken from the 12th-Century crypt to the city university forensic laboratory, where his body will undergo DNA and pathological tests.
It will then be reinterred following a Mass service at the cathedral on Wednesday. The results of the tests are not expected for some weeks.
During the war the general was prime minister of the Polish government-in-exile in London.
In July 1943, the Liberator aircraft he was travelling on together with two British MPs, crashed into the sea just seconds after it took off from Gibraltar.
The general was the leader of Poland's government-in-exile
A British investigation at the time found the plane's controls had jammed. But a separate Polish investigation did not rule out he may been murdered.
The general's death has produced several colourful conspiracy theories despite a lack of evidence.
At the time Gen Sikorski had demanded an investigation into allegations that Poland's then ally, the former Soviet Union, had massacred more than 20,000 Polish officers in the forests of Katyn three years earlier.
Some even believe British Prime Minister Winston Churchill may have ordered his death to preserve good relations with Stalin.
However, prosecutors have said they are investigating a "communist crime", suggesting that the suspicion falls on the former Soviet Union.