Poland’s justice minister says the suspect in the Kraków shooting that killed six people visited websites about Norwegian mass killer Anders Behring Breivik, pointing to what he described as a possible far-right motive.

Justice Minister Waldemar Zurek said Tuesday there was “a very strong indication of right-wing extremism” behind Saturday’s attack, Al Jazeera reported. His comments did not establish a final finding on the gunman’s motive.

Prosecutors identified the suspect as Michal Oksinski, a 24-year-old factory worker. Police said he opened fire from his car in Kraków’s historic main square before officers shot and arrested him minutes later. He died in hospital Monday.

Zurek said investigators found a firearm silencer in the car and a Gadsden flag among the suspect’s possessions. The flag features a rattlesnake on a yellow background and has been associated with the U.S. far right.

The bodies of Oksinski’s father, mother and sister were also found at their family home Saturday. Officials believe he likely killed them as well, according to Al Jazeera.

Breivik killed 77 people in Norway in 2011 in a bombing in Oslo and a shooting at a Labour Party youth camp on Utoeya island.

The investigation has prompted a political dispute in Poland. Law and Justice opposition leader Jaroslaw Kaczynski called Interior Minister Marcin Kierwinski’s earlier claim of far-right influence a “blatant lie.” Kierwinski said Tuesday he was not withdrawing his remarks but was waiting for investigators’ findings.

Sources