A Slovakian journalist and his girlfriend were found dead Sunday mysteriously while he was working on a story about possible links between the Italian mafia and people close to Prime Minister Robert Fico.

Ján Kuciak, 27 and his girlfriend, Martina Kušnírová, were found dead in their home just east of the capital, Bratislava. Police say the two were killed with the same weapon, which has yet to be found, and most likely were killed between Thursday and Sunday. Police have detained one suspect.

Kuciak’s unfished story, published Wednesday by news website, described the activities of members from the ‘Ndrangheta criminal group in agriculture, real estate and other sectors in Slovakia in connection with a senior assistant to Fico and another official close to him.

He also described one member’s business ties to Mária Trošková, a former model who is now the chief state adviser at the government office, and Viliam Jasan, who currently serves as the secretary of Slovakia’s security council, a body that deals with key security issues.

Trošková and Jasan announced Wednesday they were stepping down until the investigation into the shootings was completed but they “categorically” denied any involvement. Fico also dismissed the reports. “You link innocent people to a double murder without any evidence,” Fico said. “Don’t do it.”

Culture Minister Marek Maďarič also announced his resignation on Wednesday. “As the culture minister, I am not able to cope with the fact that a journalist was killed during my time in office,” he said. said Kuciak cooperated on the story with the Czech Centre for Investigative Journalism, the Investigative Reporting Project Italy and the international Organized Crime and Corruption Reporting Project. The Czech Centre said it had been working with Kuciak for more than 18 months.