Police in Denver were warned nearly a year before last week’s deadly spree shooting that the eventual gunman might be preparing a “devastating” attack. A German man named Andre Thiele told The Denver Post on Monday that he’d contacted police on Jan. 3, 2021, to alert them to the “undeniable possibility” that Lyndon McLeod “may commit a terrorist attack.” Almost a year later—on Dec. 27, 2021—that warning proved true as McLeod gunned down five people in a multi-city rampage before he was shot dead by police. After Thiele came forward, a Denver police spokesman confirmed they had received his tip but said there was “not sufficient evidence to file criminal charges or a legal basis for monitoring McLeod at the time.” Thiele had reportedly read several of McLeod’s books and been part of a chatroom where the author himself sometimes joined the discussion. The German man said he felt compelled to contact authorities after McLeod began to make increasingly frightening comments in the group chat. McLeod named two of his five victims in his books and even described similar attacks, the Post reported.