The 21-year-old man who carried out Austria's worst school shooting was an introverted fan of online shooting games, criminal investigators said on Thursday.
The Austrian, identified by local media as Arthur A, killed 10 people on Tuesday before killing himself at his former high school in the southern city of Graz.
Police found discarded plans for a bomb attack and a non-functional pipe bomb during a search of his home after the shooting in Graz, the capital of the state of Styria.
Police are still trying to establish a motive, but Michael Lohnegger, head of Styria's criminal investigation office, said findings indicated the man was very introverted and that his great passion was online first-person shooting games.
"He led an extremely withdrawn life; he didn't want to take part in activities in normal life outside in the real world, he preferred to withdraw into the virtual space," he told reporters.
Mr Lohnegger said the man's closest friend had been questioned and that the shooter had social contacts with fellow online gamers. Police are checking whether he had assistance from other people in the run-up to the crime.
Police said the rampage at the school lasted about seven minutes and that the man took his own life in a toilet about 10 minutes after beginning the attack.
A few minutes earlier, the man entered the school with a rucksack, then went into a bathroom to prepare for his assault.
Then he put on a weapon belt with a hunting knife, donned shooting glasses and a headset and armed himself with a Glock pistol and sawn-off shotgun, police said.
He opened fire at random on people on the second and third floors of the school, shooting off the locks to the doors in one of the classrooms he attacked, according to Lohnegger.
Most of the victims were apparently unknown to the shooter, but he did know one of the teachers who died, police said. It was unclear if that fact played a role in her death.
Police are alert to potential copycat attacks, and on Thursday, a man caused alarm at Vienna's Technical University by throwing a package into the entrance area and shouting it was going to explode. No threat was identified.
Psychological evaluation
The shooter acquired the guns legally in April and May after passing a psychological evaluation for a necessary permit, and had practised shooting at a gun club since March, police said.
Authorities said the man failed to graduate from the school, and Austrian newspaper Kronen Zeitung reported that after dropping out, he attempted to join the army but was deemed psychologically unsuitable due to his introversion.
Local media reported that the man, who lived with his mother on the outskirts of Graz, felt bullied at school and wanted revenge. Police declined to confirm this.
"There's no evidence from his private life that he ever expressed any anger or displeasure towards the school, pupils or teaching staff," Mr Lohnegger said.
Neighbours and officials in the commuter town of Kalsdorf bei Graz, where he lived, described a withdrawn, slight man who usually wore a cap and headphones, covering himself up.
Of over a dozen local residents spoken to about the shooter, few wanted to talk at all. Some said they had seen him, but none said they knew him.
The man left behind a farewell note and video in which he apologised to his family for his actions and thanked them, but they gave no indication of his motives, police said.
Questions about the bullying allegations at the Dreierschuetzengasse school where the man attended were put to its deputy head, Norbert Urabl, on national broadcaster ORF.
"Bullying is a very delicate topic. Bullying occurs on so many levels that it's very difficult to pinpoint the term bullying in this case," he said.
"But the fact is that, if bullying can be triggered, then more sensitivity is urgently needed to recognise bullying processes earlier."
If you are experiencing feelings of distress, or are struggling to cope, you can speak to the Samaritans, in confidence, on 116 123 (UK and ROI), email jo@samaritans.org, or visit the Samaritans website to find details of your nearest branch.
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