The suspected perpetrator, a 17-year-old from Kosovo, attacked a teacher at a vocational school in Essen on Friday. The woman suffered life-threatening injuries.
A possible motive related to religion is now being investigated, after film clips were found on one of the student's digital devices.
A preliminary assessment of the seized devices suggests a religiously motivated act, says the Minister of the Interior of the state of North Rhine-Westphalia, Herbert Reul, according to Westdeutscher Rundfunk.
The 17-year-old, who is a student at the school, also suffered life-threatening injuries in connection with the arrest.
