(credit: CBS)

(credit: CBS)

CENTENNIAL, Colo. (CBS4) – Authorities investigating last Friday’s shooting at Arapahoe High School say Karl Pierson had written a Latin phrase and some numbers on his arm. They suspect he had plans to attack five areas of the school.

Claire Davis

Claire Davis (credit: Davis Family)

Officials found the body of Karl Pierson in the school’s library after he shot and critically injured Claire Davis, 17. Pierson died as the result of a self-inflicted gunshot.

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The Arapahoe County Sheriff’s office said Tuesday that Pierson had used a marker to write “Alea iacta est” on his forearm. In English, that translates as “The Die Has Been Cast.”

It’s not clear so far why Pierson wrote that statement, and it’s also not clear why he had numbers written on his arm. Sheriff’s officials described their investigation into that with the following statement:

The shooter had also written five separate letters/numbers on his arm, numbers which correlate directly with the identification of the Library and specific classrooms located in the immediate area of Library/Media Center of the Arapahoe High School. The letters/numbers written on the shooters arm is an indicator to investigators of the shooter’s plan. Teams of Sheriff’s Office Investigators will attempt to determine the relevance of the list of numbers written on the shooter’s arm to specific classrooms, while closely evaluating if the occupants of those classrooms may have also been targeted for harm by the shooter.

The sheriff’s department also summed up all of the weapons Pierson carried as he walked into the school at 12:33 p.m. before shooting Davis and then shooting himself.

– 12 gauge pump action shotgun

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In a backpack:

– three (3) functional Molotov cocktails
– a machete in a canvas scabbard

In two bandoliers across his chest and waist:

– more than 125 rounds of assorted types of shotgun ammunition

Officials said Pierson also randomly fired the gun several times in the school without injuring someone.

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