The perpetrator, who had four prior criminal convictions, admitted to pouring 8 liters[1] of gasoline into plastic bottles at a nearby petrol station and going to his son's flat.

According to the remand request filed by State Attorney Michal Król, the perpetrator had planned the attack in advance.

He consumed alcohol in order to strengthen his resolve, filled two plastic bottles with gasoline at a nearby petrol station, and went to the flat with full knowledge of the birthday party that was taking place inside.

The perpetrator stood in front of the entrance doors with open bottles of gasoline in each hand and rang the doorbell.

Thereafter, the perpetrator threw one of the open bottles at the female victim, who reacted by slamming the doors shut.

Several weeks before the arson attack, the perpetrator threatened his wife and son with a gas pistol at a nearby lake.

[12] Initial investigations conducted by the police revealed that the fire was deliberately set and concluded the incident was an arson attack.

[13] Police officials detained Konopka, who is accused in connection with the incident, and during an interview with Česká televize, regional police chief Tomáš Kužel compared the incident to the 2013 Frenštát pod Radhoštěm explosion which eventually killed seven people.

[1] The attack was the worst mass murder in post-WW2 Czech history (see list of massacres) until the 2023 Prague shooting.

The January 2020 Vejprty care center fire was also started deliberately according to investigators, however no one has yet been charged with causing the 8 deaths therein.