Marián Kočner is a Slovak criminal operating mostly in the spheres of risk investment, financial development and property business. His name appeared in so-called "mafia lists" - a set of documents allegedly leaked by police in 2005 containing a list of people suspected of involvement in organized crime and of vehicles used by them, intended as an aid for police patrols. Kočner's business practices had been a prominent topic of articles by Ján Kuciak, an investigative journalist from Aktuality.sk who was murdered in February 2018. A couple of months prior to Kuciak's death, Kočner had allegedly threatened in a phone call to "dig up dirt" on Kuciak, saying "I will focus especially on you, your mother, your father, on your siblings.". Kuciak had filed a criminal complaint but a subsequent police investigation concluded that Kočner's alleged statements did not constitute a criminal offence. After Kuciak's murder, general prosecutor Jaromír Čižnár ordered the case to be reopened. However police again closed the case concluding that Kočner's statements did not constitute a criminal offence. Aktuality.sk subsequently published transcript of the phone call between Kuciak and Kočner. Kočner is also connected to Alena Z. via Alena Z.'s daughter as her godfather.
Kočner first gained public notoriety for his attempt to take over TV Markíza in 1998. TV Markíza, one of the first private television channels in Slovakia, was founded by Pavol Rusko and Sylvia Volzová in partnership with CME Media Enterprises B.V. in 1996. Initially the channel was not successful in acquiring a broadcasting license, licensing board objected that Rusko did not disclose Volzová as co-owner. Rusko had entered into an agreement with Espé štúdio, a company owned by Siloš Pohanka to pay 3 million DEM in exchange for help getting a broadcasting license for Markíza. Eventually the cast of licensing board changed, Markíza secured the broadcasting license and launched on 31 August 1996. However Rusko declared the agreement with Espé štúdio invalid, as he argued that Markíza had acquired the license without the help of Siloš Pohanka. After unsuccessful attempts at getting money from Rusko, Pohanka sold his claim to Gamatex, a company owned by Kočner. Kočner persuaded Volzová to acknowledge the claim and Kočner started court procedures to have the claim paid out. In August 1998 Kočner appeared at the Markíza offices with a court order giving him control over the TV station. When negotiations with Rusko regarding the ownership dispute failed, Kočner occupied the TV station with hired private security and fired TV channel's top managers. This caused public outrage, as the takeover took place only 10 days before parliamentary elections. At that time TV Markíza was deemed the main news outlet opposing the government of Vladimír Mečiar and the attempted takeover was considered an attack on press freedom. Several thousand of angry citizens gathered in front of Markíza's offices as a show of support and several politicians from opposition parties gave speeches at the rally. After two days, Kočner and his associates left the building and ownership dispute continued in courts. According to news reports, Kočner's involvement in TV Markíza seemingly ended in 2000 when Rusko bought Gamatex through intermediaries. In a 2006 interview with aktualne.sk Kočner said the security firm involved in the takeover of Markíza belonged to Peter Čongrády, a local mafia boss. However in later interviews he denied hiring Čongrády. In June 2016 Kočner's company "Správa a inkaso zmeniek" initiated court proceedings against Pavol Rusko and TV Markíza to collect money owed to him under four promissory notes amounting to approx. €69 million. Kočner claimed that Rusko had issued the promissory notes in June 2000 with Markíza providing endorsement for the notes. At the time Rusko was the executive director of TV Markíza as well as one of its shareholders. Two of those notes amounted to €8.3 million each with a maturity date in 2015 and another two were signed as "blank cheques" in the amount of €26 million with a maturity date in 2016 added later. Rusko acknowledged Kočner's claim in court and declared that the promissory notes were intended to resolve the ownership dispute with Gamatex. Markíza's management was unaware of the existence of the promissory notes. They were not recorded in either company's accounting and were not discovered during the preparation of the due diligence report when CME became the sole shareholder in TV Markíza. In April 2018 a court declared Kočner's claim as valid. However, in retaliation TV Markíza filed a criminal complaint against Kočner and Rusko for forging the promissory notes. In addition, an investigation into possible tax evasion began as, by not disclosing possession of the promissory notes to tax authorities, Kočner's companies avoided paying tax on interest on the notes. In June 2018, Kočner was detained by the Slovak authorities in the case of the promissory notes forgery together with Pavol Rusko, as well as for various tax-related crimes. On 8 March 2019 Marian Kočner was formally charged for having ordered the murder of investigative journalist Jan Kuciak in February 2018. Kočner remains in custody as of December 2019. Since 10 December 2019 he has been included in the global Magnitsky sanctions list. On 27 February 2020, Kocner was sentenced to 19 years of jail for forging $75 million worth of promissory notes to siphon money from Markiza.