No, although they did buy their guns at the same gun shop.
Dylan Klebold was born on 11th September 1981, 20 years before 9/11.
William Atchison and David Ali Sonboly talked online, with it being said that Sonboly gifted Atchison GTA V on Steam.
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"One day I might just disappear and you will never find me. Nobody will ever find me"