Kocner’s Library

Country/area: Bosnia and Herzegovina

Organisation: investigace.cz, The Investigative Center of Jan Kuciak, OCCRP

Organisation size: Big

Publication date: 21 Feb 2020

Credit: Pavla Holcová, Arpád Soltesz, Eva Kubaniova, Friedrich Lindenberg, Jurre Van Bergen, Olga Gein, Martin E., Adriana Homolová

Project description:

In late 2019, reporters at the Investigative Center of Ján Kuciak and Investigace.cz obtained the complete police case file on the 2018 murders of investigative reporter Jan Kuciak and his fiance Martina Kusnirova. A total of 53 TB of material, the archive included materials that implicated businessman Marian Kocner and officials in corrupt activities. OCCRP’s data and tech teams spent 4 months wrangling the massive amount of information and setting up “Kocner’s Library,” a secure leak room in Bratislava with viewing stations where journalists could explore the material and then “check out” specific files for offline study.

Impact reached:

The journalists created and coordinated a team of about 20 top Slovak journalists from trustworthy Slovak media. The team was designed to reach to wide audience and cover all possible needs of a good investigative team – there were analysts from dailies, TV stations and even journalists from tabloid.


The unusual arrangement of Kocner’s Library gave a team of journalists in Slovakia free access to the information from the leak to follow and investigate leads that hold power to account. Equally important was securing the police file during the trial of Marian Kocner to ensure a free and fair judicial process.


Reporters showed how Kocner secured influence with threats, bribery, and blackmail of public officials, sometimes by recording audio and video of meetings with them. During multiple raids in 2020, Slovak police arrested 20 judges, including judges from the supreme court, who allegedly took bribes for ruling in favor of Kočner´s interest or leaked sensitive information to him. . Apart from the 20 judges, one constitutional judge resigned because of his ties to Marian Kocner, one bankruptcy trustee, three lawyers and four other people were arrested. 


Slovakia’s police chief and the head of its financial crimes unit both resigned following media reports that information about Kuciak in police databases had been accessed prior to the murders. As an indirect impact of the project, eight top officials including two police presidents were put into custody. 


A prosecutor was suspended after footage leaked to OCCRP appeared to show him setting up a camera in what looks like his office with someone who appears to be Kočner. He was later charged with abuse of office. Slovak Office for protection of private data threatened investigace.cz with 10 000 000 eur penalty if they wont reveal a source of the footage.

Techniques/technologies used:

We set up a room in Bratislava with five laptops with immutable operating systems that would have access to the data located on a remote server. After we’d managed to upload all the material, we made a cleanup copy of it, unpacking all contained evidence and removing unnecessary and system files. We started a process of identifying key pieces of evidence in the folder hierarchy, linking them into an easy-to-use reporter’s desktop and documenting the meaning of the material as we discovered it in a wiki. Eventually we indexed key portions of the material into OCCRP’s data platform, Aleph.

Key technologies: Linux, hashdeep, Aleph, Cellebrite, Fedora Silverblue, Wireguard, fastai+torchvision, Leaflet.js


What was the hardest part of this project?

There were three challenges: 1. figuring out how to make the material available to journalists within certain limits, 2. how to handle the incredible amount of data and 3. coordinating between the journalists.


The main challenge of this project was to provide access to the vast police evidence file to Slovak and Czech reporters in such a way that they can report from it, while also controlling the outflow of information to establish some accountability for how the material is used. That need for accountability resulted in particular from the presence of sensitive personal information of the victims and the accused in the data, as well as the existence of unpublished political kompromat (e.g., video of the minister of finance making back-room deals).


The volume and nature of this data forced us to study and apply multiple digital forensics techniques in order to make the material accessible to reporters. It has also given us a more systematic understanding of how experts in related fields — especially law enforcement — handle evidence. 


Another challenge was coordination of the team of journalists from various competing media. At the end, the team coordinated deadlines, shared their findings and helped each other in unprecedented ways. The impact of publishing the investigative stories in all major media at the same day multiplied its effect on audience and really created public pressure for a change.

What can others learn from this project?

Journalists are accessing the material in Kocner’s Library to further investigate Slovakia’s government and judicial system in the continued push for justice. They also learned how to cooperate better.

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