Ján Kuciak and Martina Kusnirova were shot dead in Slovakia's capital Bratislava in February 2018. The murder led to mass demonstrations in the country and Prime Minister Robert Fico was forced to resign.

The prosecutor believes that the entrepreneur who has been the focus of Kuciak's corruption report ordered the murder. The entrepreneur and two suspected aides deny the charges, while the fourth person accused has admitted to the shooting, Reuters news agency writes with reference to the Slovak television channel RTVS.

A fifth man has admitted that he was involved in facilitating the murder and will, after a settlement with the prosecutor, testify.

"The situation has deteriorated dramatically"

After Thursday's preliminary hearing, the judges will either set a date for the main hearing or ask prosecutors for further evidence, Reuters writes.

- In Slovakia, the situation has deteriorated dramatically over the past three years. They have gone from being a country comparable to the Nordic in terms of freedom of the press to being a country where freedom of the press is very poor. Journalists are identified as the nation's enemies and many have resigned from their public service jobs, says Erik Halkjaer, President of Reporters Without Borders.