(CNN)Slovak police have detained seven people in connection with the slaying of investigative journalist Jan Kuciak and his fiancée, the state news agency TASR reported.
The couple was found shot to death in Kuciak's apartment in western Slovakia earlier this week.
The individuals being detained, who are between 26 and 62 years of age, are believed to have ties to Italian organized crime, Police Corps President Tibor Gaspar stated at a news conference Thursday, according to TASR.
The people were detained after police raids in the Kosice and Presov regions.
Kuciak, 27, and Martina Kušnírová were found dead Monday with bullet wounds to the chest and head, respectively, according to the International Press Institute. They were shot at Kuciak's apartment in Velká Mača sometime between Thursday and Sunday, police said.
Kuciak reported on tax evasion and fraud among Slovak businesses, including people connected to the country's governing party, Smer.
On Wednesday, Aktuality.sk published the last unfinished report Kuciak was working on before he was killed.
The government of Slovakia said Monday it was offering a reward of 1 million euros ($1.2 million US) for information about the killing.