[4] At the end of September 2001, he had spent a few days away from school, for which he presented a mandatory medical certificate which was quickly identified as a forgery.

[2] The investigation revealed that Steinhäuser had been using the Internet to research the Columbine High School massacre, and had related files saved on his computer.

[7] On the day of the shooting, before leaving his residence at his usual time, Steinhäuser armed himself with a 9mm Glock 17C semi-automatic pistol, a Mossberg 590 Mariner 12-gauge pump-action shotgun,[8] which was unusable due to an earlier handling error, and a diving knife.

Steinhäuser entered the school unmasked at approximately 10:45, carrying his weapons and ammunition concealed in either his sports bag or backpack.

The gunman had killed 16 people: the school's assistant principal, secretary, ten teachers, one trainee-teacher, two students, and one police officer.

[15][16] Steinhäuser's family issued a statement to news sources saying that they "will forever be sorry that our son and brother has brought such horrifying suffering to the victims and their relatives, the people of Erfurt and Thuringia, and all over Germany.

[9] The state government of Thuringia reprimanded the principal of the school for the expulsion of Steinhäuser, saying she had overstepped her legal powers and violated the rules of the procedure.

[6] In response to the shooting, a law was enacted that would give high school students the option to take an exam at the end of the 10th Grade at their own request.

According to the report of the Gutenberg Commission, Steinhäuser had some violent movies such as Fight Club, Predator and Desperado, as well as the video games Return to Castle Wolfenstein, Hitman: Codename 47 and Half-Life.

The discussions contributed to a revision of the Protection of Young Persons Act and helped to strengthen the rules for these legal areas.

[20] Steinhäuser's last words – Für heute reicht's ("that's enough for today") – was also the title of a controversial book about the massacre written by Ines Geipel, who alleged that there were several mistakes made by the police on the case.

While police patrols were previously required to wait for a special task force, policemen all over Germany now get the necessary training and equipment to deal directly with mass shooters.

[6] Heise was hailed as a national hero for locking Steinhäuser in a room, which ended the killing spree, but was later subject to backlash from some members of the public due to questions about his role.

Erfurt Mayor Manfred Ruge said he fully believes Heise, but acknowledged the teacher's rather direct and animated style combined with the vast media coverage had caused resentment in the town.

[23] Steinhäuser was mentioned in a video created by Pekka-Eric Auvinen, who killed eight people during the Jokela school shooting in Finland.