In the preliminary investigation, there is extensive evidence that shows that the 15-year-old has been preparing for a long time and has also spread his plans on internet forums.
The seizures made by the police during the preliminary investigation include a list where the 15-year-old wrote down all the classes in the school and made notes about which students and teachers he intended to kill in each individual class.
Drawn map on the arm
During the act itself, the 15-year-old has drawn a map on his arm that shows which class is in which classroom during the time he planned to perform the act.
Criminal plan and manifesto
In a criminal plan that he sent to an acquaintance, it can be seen that the act is planned.
The perpetrator has planned what he will wear, what weapons he will wear and when he will enter the school.
It is also possible to read that the final plan is to be shot by the police.
Among the evidence is also a manifesto in which the 15-year-old where he quotes the perpetrator of the Christchurch mosque shootings in New Zealand in 2019. The manifesto also contains several other references to Nazism as well as to other similar school attacks.