From The Denver Post: Five of the state’s largest school districts have investigated more than 400 threats by students this school year and put 40 of them at the highest levels of concern, according to records obtained by The Denver Post.

But more than a month after the fatal shootings at Arapahoe High School, administrators at Littleton Public Schools still won’t say whether a threat made by gunman Karl Pierson in September prompted the district’s highest security response.

In the noon hour on Dec. 13, Pierson, a senior at Arapahoe, entered the school through a door that was propped open. The 18-year-old — armed with a shotgun, a machete, three Molotov cocktails and more than 125 rounds of ammunition — killed student Claire Davis and took his own life inside the library.

Littleton was among school districts across Colorado that bolstered protocols for identifying the severity of threats and fashioned response plans after the 1999 shooting at Columbine High School in Jefferson County left 13 people dead. The two gunmen, both Columbine students, then killed themselves.

Littleton schools did not respond to a request for the number of threats by students, but surrounding districts — Denver, Jefferson County, Cherry Creek, Aurora and Douglas County — provided figures.

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