Poland's Catholic Church is launching a fresh investigation to identify church collaborators who worked for the communist-era secret police.
The late Pope John Paul II is revered across Poland
"The issue simply has to be investigated... we should not fear the truth," said Father Robert Necek, spokesman for the Church in Krakow.
Church historians will look through secret police files for evidence of collaboration, the AP news agency says.
The Krakow inquiry follows Church investigations elsewhere in Poland.
The Church commission was launched by the Archbishop of Krakow, Cardinal Stanislaw Dziwisz, who was formerly personal secretary to the late Pope John Paul II.
Cardinal Dziwisz said the communist era had been "a time of persecution of the Church, often bloody and brutal".
Last April the Polish Church was shocked by the case of Father Konrad Hejmo, a Polish priest who admitted taking money from an alleged secret service agent while working at the Vatican.
Poland's Institute of National Remembrance, a body investigating communist-era collaboration, accused him of helping the secret services in the 1980s. He denied spying, however.
Polish-born Karol Wojtyla, the priest and archbishop who went on to become Pope John Paul II, stirred great pride among most Poles.
One of the darkest episodes for Polish Catholics in the communist era was the abduction and murder by security agents of a pro-Solidarity priest, Father Jerzy Popieluszko, in 1984.