Acord, a juvenile, will be charged "as an adult with attempted aggravated murder, " Haroldson said.

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The 1999 shooting spree at Colorado's Columbine High School served as Grant Acord's benchmark and inspiration, Benton County District Attorney John Haroldson said.

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With the help of explosive devices, checklists and diagrams, Acord's "goal was to model the Columbine shootings with some adjustments that would make it a greater success, " Haroldson said.

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They recovered napalm, pipe and drain cleaner bombs, as well as Molotov cocktails Friday from "a secret compartment that had been created in the floorboards" of the teen's bedroom, Haroldson said.

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