Thirteen judges in Slovakia and five other people linked to the main suspect in the case of murdered investigative journalist Jan Kuciak have been detained and charged with corruption and obstruction of justice, Slovak police said Wednesday.

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Police did not provide the identities of those detained, according to AP, but the move was announced by a special police unit investigating contact between several judges and businessman Marian Kocner.

Kocner was charged on Wednesday with bribing the judges, his lawyer Marek Para told local media. Police and prosecutors declined to provide more details.

Kocner and three other defendants are currently on trial over the killing of reporter Kuciak and his fiancée Martina Kusnirova on 21 February 2018, a crime to which he has pleaded not guilty. The defendants face potential prison sentences of 25 years to life if convicted of murder.

At the time of his killing, Kuciak had been writing about alleged ties between Italian mafia groups and individuals close to the Slovakia's then prime minister, Robert Fico. 

Kocner, who had close ties to senior figures close to Fico, allegedly hired a Slovak former intelligence official to carry out surveillance on Kuciak before his killing.

The 2018 killings of Kuciak and Kusnirova triggered major street protests and a political crisis that led to the collapse of Fico's government and the dismissal of the national police chief.

The investigation disclosed that Kocner created a wide network of contacts with politicians, judges and prosecutors, who allegedly helped him with his business dealings.

The fallout led to shock results in Slovakia's March elections. The opposition Ordinary People party, or OLANO, beat the ruling SMER Social Democrats, which Fico formerly led, by more than six points.

Kocner was sentenced to 19 years in prison in February in a separate case over forgery and securities crimes.