The 18-year-old gunman who opened fire at a crowded Munich shopping mall and fast-food restaurant, killing nine people and wounding 16 others before killing himself, was obsessed with mass shootings, police said Saturday.
Investigators searched the unnamed German-Iranian man's home overnight and found a considerable amount of literature about mass killings, including a book titled "Rampage in Head: Why Students Kill," but no evidence that he was linked to extremist groups such as the Islamic State of Iraq and Syria, or ISIS.
They believe he acted alone.
"Documents were found about mass shootings," Munich's police chief Hubertus Andrae told reporters. "The perpetrator was obviously obsessed with the issue."
Robert Heimberger, the head of Bavaria's criminal police, said it appeared the shooter had hacked a Facebook account and sent a message inviting people to come to the mall for a free giveaway.
The suspect's body was found about 2 1/2 hours after the attack, which started at a McDonald's restaurant across the street from the mall. He was found with 9mm Glock pistol and at least 300 rounds of ammunition, police said.
Munich's mayor, Dieter Reiter, declared a day of mourning for the victims of "this terrible act."
"These are difficult hours for Munich," he said, adding that the city's citizens had shown great solidarity toward each other. "Our city stands united," he said.
The Associated Press contributed to this report.