Karl Pierson's alleged murder plan at Arapahoe High: "The die has been cast"

Update: Following Friday's shooting at Arapahoe High School, Arapahoe County Sheriff Grayson Robinson hinted that what some initially interpreted as a limited attack by gunman Karl Pierson, with librarian/debate-team coach Tracy Murphy as the single target, was actually a broader plot for death and destruction. Now, Robinson's office has unveiled chilling details to reinforce this theory, including assorted scrawlings on his arm -- school room numbers plus a Latin phrase that translates to "The die is cast." Get more information and see photos and video below.

The latest Arapahoe County Sheriff's Office release traces last week's events with unsettling precision. Just before 12:33 p.m. on Friday, Pierson is said to have gained access to Arapahoe High through the school's north entrance.

He wore a backpack and was armed with a .12 gauge pump action shotgun, three Molotov cocktails, a machete in a canvas scabbard and more than 125 rounds of shotgun ammunition -- steel-shot, buckshot and slug -- worn in two bandoliers slung across his chest.

The latest account further debunks early reports about a confrontation between Pierson and the student he shot: Claire Davis, seventeen, who remains comatose in critical but stable condition at Littleton Adventist Hospital. The ACSO believes Pierson immediately began firing the shotgun as he stepped inside the building, with the second blast striking Davis, who just happened to be in the vicinity.

In the next minute or so, Pierson fired the shotgun three more times before taking his own life in Arapahoe's library/media center -- an area Murphy had already exited in what Robinson called an important tactical decision.

Upon examining Pierson's body, personnel with the Arapahoe County coroner's office discovered a Latin phrase -- "Alea iacta est" -- scrawled on his forearm in what's described as indelible marker.

These words, which translate to "The Die is Cast," have long been a popular tattoo, as witnessed by this image....

...and this one: In addition, the coroner discovered five separate letters/numbers that correlate with the library and other classrooms in the school's media center area, the ACSO divulges.

The conclusion of the sheriff's office: The numbers are indicative of a "shooter's plan" -- presumably one intended to take many lives and inflict even greater damage.

The inquiry is far from over. The ACSO characterizes the continuing investigation "robust" and "ongoing" as well as "deliberate" and "methodical," which implies that these are hardly the last revelations likely to emerge about this terrible day.

Regarding Davis, this is the most recent post on the Littleton Adventist Hospital Facebook page about her:

As of 5 p.m. [Tuesday], nearly 100 cards and notes have been brought to the hospital for Claire and her family. We'd like to recognize the local elementary school who brought by a large envelope of notes and drawings from their students.

Additionally, TLC Meals on Wheels has received $700 in donations and $1,500 has been donated to the Littleton Hospital Foundation for local youth mental health awareness and support programs on Claire's behalf.

Thank you all very much for your outpouring of support. Please continue to keep Claire and her family in your prayers.

Here's a CBS4 report about the latest developments.

Send your story tips to the author, Michael Roberts.

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