Most of the publicly available information about his criminal activities and contacts with the politicians leaked from police archives (which include wiretapping records and Mrázek's own collection of blackmail material) after his death.

He "dealt" in a variety of articles including wristwatches, Walkmans and textiles of Western origin, and even with gravestones from Czech Jewish cemeteries.

[5] He was also involved in the criminal underground of the Kolín region as his name appeared in the circles of foreign currency speculators (Czech: veksláci).

[citation needed] Together with his business partners, he took the opportunity offered by the chaotic situation at the beginning of Czech economic transformation, and laundered the dirty money from the past.

[13] At the beginning of the 1990s, Mrázek, together with famous Czech singer Karel Gott, established the foundation Interpo, dedicated to helping children of police officers killed in the line of duty.

[11] In January 2000 Mrázek joined developer Luděk Sekyra in an attempt to acquire major Czech construction company IPS.

[19] Former Czech Minister of Finance Ivo Svoboda negotiated the sale of the debt with Austrian entrepreneur Barak Alon and also with Mrázek.

[20] František Mrázek was in long-term contact with Miroslav Šlouf, the chief-consultant of former Czech Prime Minister Miloš Zeman.

[24] On 25 January 2006, František Mrázek was shot and killed by an unknown assailant in Durychova Street, Prague 4, in front of the registered office of his firms and companies.

[25] Jaroslav Kmenta, the chief-reporter of the Czech daily newspaper Mladá Fronta Dnes, published information on František Mrázek in three books.

The reliability of his investigation was however questioned and on 21 November 2008 Kmenta stated: "...in agreement with the editor-in-chief, I published only absolutely verified information, derived from various sources".

[31] In February 2009 the Czech parliament amended criminal law with an explicit ban on publishing any account of police wiretapping, under penalty of a heavy fine and years of imprisonment.

The law was criticised by the Czech media as an attempt by politicians to avoid future embarrassment akin to the Mrázek case.