[2] Subsequently, in 2007 he published his controversial book Księża wobec bezpieki na przykładzie archidiecezji krakowskiej [pl] (lit.

[4][5] He is the subject of a documentary 'Poland's Turbulent Priest', shown on BBC World News in 2009, about his struggle with the communist regime and the Polish church.

In 1980, Isakowicz-Zaleski became engaged in the Solidarity movement;[1] three years later he was ordained and chosen to continue studies at the Papal Armenian Collegium in Rome.

Isakowicz-Zaleski began working in Kraków's district of Nowa Huta, where he celebrated Mass for the workers and for the fatherland in the Maximilian Kolbe parish in Mistrzejowice.

In 2006, after months of research at the Institute of National Remembrance, he drafted a book on the collaboration between Catholic priests and government agents.

In November 2006, he received an apology from the nation's Catholic primate, Cardinal Józef Glemp of Warsaw, for earlier criticizing his research into collaboration between the clergy and the Communist-era secret police.

In September 2007, Polish Ombudsman awarded him the Order of Pawel Wlodkowic for courage in fighting for basic values and truths, against the opinions of the majority.

[20] In 2008 he wrote the book Subdued Genocide in Kresy, in which, among other things, he described the fate of his family and of the village of Korosciatyn near Monasterzyska (area of Ternopil), which was destroyed by Ukrainian nationalists, and its inhabitants murdered.

[21] He frequently criticized not only members of the Polish Government, together with President Kaczynski but also Roman Catholic hierarchy, such as Primate Józef Glemp and Cardinal Stanisław Dziwisz, claiming that they neglected the sufferings of Poles in Western Ukraine and they did not protest when Ukrainian nationalists are awarded orders.

Subsequently, he found some five hundred pages of material on himself alone, names of fellow priests who had allegedly spied on him, and also a video of himself being gagged and beaten by thugs.

[24] Thus, he appealed publicly for all the priests who had served as secret agents for the Security Service to step forward and reveal themselves, causing a furore.

[25] His activities were harshly criticized by the Kraków Curia and Zaleski received an order from his superiors to refrain from making public statements about this subject.

Cardinal Stanisław Dziwisz stated that Isakowicz-Zaleski had received a permit to conduct research exclusively into the repression that he himself faced under communism.

[25] Dziwisz condemned his "irresponsible and harmful" activities in a public letter, warned him to stop "throwing accusations",[24] and finally ordered him to be silent.

[5][29] On 28 February 2007, Znak publishing house issued Zaleski's book Księża wobec bezpieki na przykładzie archidiecezji krakowskiej (Polish Priests and the Communist Secret Police, ISBN 978-83-240-0803-2), in which he addressed the topic of the extent to which Poland's Roman Catholic Church was infiltrated by communist security.