David Sonboly, the 18-year-old who killed nine people during a shooting rampage in Munich on Thursday, had seemingly been planning the attack for a year.
It also appears that he chose his target at random, without any apparent political or racial motivation.
Sonboly began shooting outside a Munich shopping centre last Thursday evening, killing nine people, mostly teenagers.
58 shell casings were recovered from the area, all fired from a Glock 9mm pistol that Sonboly had illegally sourced via the internet. 300 bullets were found in his backpack.
A link has been established between Sonboly and Norwegian mass murderer Anders Behring Breivik, who slain 77 people in Norway exactly five years to the day when Sonboly carried out his own attack. It also appears that Sonboly had an admiration for 17-year-old Tim Kretschmer, who killed 16 people in Winnenden school in 2009.
Investigators combing through Sonboly’s past have painted a picture of a loner, bullied individual without any academic qualifications, and severe psychological issues.
Sonboly shot himself dead after being injured by police.