BRATISLAVA, Slovakia (AP) — An investigative journalist shot dead in Slovakia last week was working on a story about the activities of the Italian mafia in his country and their links to people close to Prime Minister Robert Fico.

Jan Kuciak's news website published his last, unfinished story Wednesday. It describes the activities of members of the Italian 'Ndrangheta criminal group in eastern Slovakia, and the business ties of one of them with a senior assistant to Fico and another official close to him.

The bodies of the 27-year-old Kuciak and his girlfriend, Martina Kusnirova, were found Sunday evening in their house in Velka Maca, east of the capital, Bratislava. Kuciak was the first journalist to be slain in Slovakia.

In his story he described, among other details, the activities in agriculture, real estate and other sectors of a Slovak-based Italian man believed to belong to the criminal group.

He also detailed the man's business ties to Maria Troskova, 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.

In a joint statement, Troskova and Jasan announced Wednesday they were stepping down until the investigation into the shootings was completed.

They said they were shocked by the slayings and expressed their condolences to the relatives. But they "categorically" rejected any links to the killings.

After the first details of the story appeared in and a newspaper, Sme, on Tuesday, Fico dismissed the reports.

"You link innocent people to a double murder without any evidence," Fico said. "Don't do it."

The opposition wasn't impressed and called on national police chief Tibor Gaspar and Interior Minister Robert Kalinak to resign.

A thousand people attended a protest rally organized by the opposition in Bratislava.

Culture Minister Marek Madaric announced earlier Wednesday that he was resigning from his government post.

Madaric, a member of Fico's leftist Smer-Social Democracy party, said it was his personal decision.

"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.

Also Wednesday, Justice Minister Lucia Zitnanska, from a junior coalition partner of Fico's Smer, said it was "absolutely unacceptable" that anyone with ties to organized crime would be working at the government office.

Students plan marches to honor Kuciak in a number of Slovak cities on Friday.

Gaspar, the police chief, said on Wednesday "one of the most likely versions" still was that Kuciak was killed because of his investigative work.

Giving few details, Gaspar said the two were killed with the same weapon which police still don't have.

Gaspar said that during the investigation in an unrelated case, police found out two people known for drugs related crimes were planning to meet in Velka Maca on Friday and take guns with them.

Police estimated the killings took place between Thursday and Sunday. He said another suspected person was seen in the town.

Gaspar said police conducted raids during which they seized some ammunition and a weapon. One suspect was detained. He said police still were investigating what the two were planning to do in Velka Maca. 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 center said it had been working with Kuciak for more than 18 months.