(CNN) A controversial Slovak businessman has been charged with ordering the murder of an investigative journalist and his fiancée last year, prosecutors said Thursday.

Prosecutor Dusan Kovacik said Marian Kocner, an entrepreneur who was director of an organization that closed in 2017, ordered the murder of Jan Kuciak and his fiancée Martina Kusnirova.

"On 8 March the prosecutor's office formally charged Marian K for having ordered the murder of investigative journalist Jan Kuciak," Kovacik said in a statement according to the news agency Agence France-Presse. "The reason for the murder was the journalistic work of the victim. We don't have a weapon, but we have evidence of the weapon and ammunition."

Kocner is already in custody in the city of Banska Bystrica, accused of economic crimes.

Thousands of Slovaks attend a protest in Bratislava on the first anniversary of the murder.

Kuciak and Kusnirova, both aged 27 at the time of the attack, were found dead in the journalist's apartment in February 2018 with bullet wounds to the head and chest respectively.

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