Arapahoe High School shooting report: School, district made series of errors before deadly shooting

Claire Davis, 17, was shot and killed in 2013

LITTLETON, Colo. - Investigators who looked into the deadly shooting at Arapahoe High School say "many small errors" were made and there were "many missed opportunities" to intervene with the gunman prior to the shooting.

The report released Monday was done by The University of Colorado Center for the Study and Prevention of Violence and the University of Northern Colorado's Department of Criminal Justice. It was commissioned by the Arapahoe High School Community Fund Honoring Claire Davis, a donor advised fund of The Denver Foundation.  The purpose was to understand the school’s threat and risk assessment procedures and responses.

Senior Karl Pierson shot and killed fellow student Claire Davis on Dec. 13, 2013, and then killed himself.

The report’s findings revealed three major failures within AHS and Littleton Public Schools in the months and years leading up to the shooting:

  1.  a failure of information sharing
  2.  a failure of threat assessment
  3.  a failure of systems thinking

According to the report, there were "many missed opportunities" to share information about the gunman's "concerning behaviors" and to intervene with the gunman before the shooting.

“There was no vortex for all the information for all the information to be collected in one place,” said co-author William Woodward of CU’s Center for the Study and Prevention of Violence. “The information about earlier problems (in elementary school) and around the time of the original threat wasn’t shared.”

"...[T]he Sheriff’s Report clearly states that at least ten AHS students had substantive concerns about [the gunman's] anger problems and gun ownership prior to the shooting, but only one student reported their concern to a counselor and no students reported their concerns to Safe2Tell," the report states.

“A lot of kids weren’t especially trained around Safe2Tell,” Woodward said. “As a result, kids didn’t end up calling and yes, a lot of kids knew about the gun and a lot of kids knew about how angry he was and a lot of kids knew about an event in a different classroom where he ended up slamming his hand down and upsetting a lot of kids.”

"If just one student or teacher, had called Safe2Tell, this tragedy might have been averted," said the report, referring to a tip line for reporting possible threats. 

Authorities believe the gunman was targeting his debate coach when he entered the school with a shotgun, machete, homemade bombs and 125 rounds of ammunition. Investigators said he shot and killed Davis, 17, before turning the gun on himself in the school library as security officers closed in. The coach escaped unharmed.

Two school security guards told investigators they saw the gunman looking at pictures of guns and mass shootings on his computer six weeks before the shooting. Also, police found a book about the Columbine High School attack when they searched his mother's home.

Arapahoe County Sheriff Dave Walcher said school officials did not suspend the gunman in September and allowed him to return to class after he threatened to kill the debate coach, who had recently demoted him as captain of the team.

“We don’t want to be overly critical of Arapahoe High School,” Woodward said, “but yes, their own policies and procedures were not followed in terms of how you complete a threat assessment.”

He also said the myriad of small issues with “systems thinking” ended up “putting Karl Pierson in a position where he could commit the crime he committed.”

The report listed a series of errors the school and the school district made involving the gunman (referred to as "KP"):

  • Decision to not build a safety and support action plan for KP after incidents of violence in elementary school, when early violence is clearly a strong risk factor for later violence
  • Decision to ignore the possible impact of his parent’s divorce
  • Decision to not enlist the help of one adult at AHS that KP trusted in his safety and support action plan
  • Decision to not have a safety and support action plan (e.g., mental health referrals, follow-up meetings) when KP yelled “f***” in class and was suspended
  • Decision to not follow-up on KP’s use of inappropriate “penis” line in debate competition
  • Decision to not follow up on KP’s claims of being bullied by others and being a bully to others
  • Decision to not empirically validate LPS’s threat and risk assessment tool
  • Decision to not treat KP’s violation of the Assistant Principal’s request that he not attend speech and debate team practices as evidence of “boundary probing”
  • Decision to only use two threat assessment team members in the threat assessment process, despite state and federal guidelines
  • Decision to leave the School Resource Officer out of the threat assessment process
  • Decision to not assign a staff member to serve as the “information vortex” for KP during the threat assessment
  • Decision to not have a district-level Safe2Tell training policy for high schools
  • Decision to not forward KP’s threat assessment to the district for review
  • Decision to not thoroughly check the facts and collect collateral information on KP in the threat assessment process
  • Decision to not tell a student’s teachers the reason for a threat assessment, detention, or suspension
  • Decision to train threat assessment using only didactic and audio visual resources 
  • Decision to not formally suspend KP for his threat to “kill” Mr. Murphy (the debate coach)
  • Decision to not formally suspend KP for his outburst in Ms. Lombardi’s Spanish class
  • Decision to not obtain video surveillance footage of KP making a threat about Mr. Murphy in parking lot
  • Decision to allow KP to return to school without the threat assessment team obtaining release of records from KP’s private therapist
  • Decision to allow KP to stay in school, when requested release of mental health records was not provided, as requested
  • Decision to only have one follow-up meeting to discuss KP’s progress with the safety and support action plan
  • Decision to not recommend a Student Intervention Team (SIT) to support KP when his grades began to decline
  • Decision to not inform the threat assessment team about KP’s viewing of guns and mass shootings on his laptop
  • Decision to not search KP’s computer, locker, or possessions for confirmation of his viewing of guns and mass shootings
  • Decision to not report KP’s purchase of a gun or interests in guns, as well as his anger problems, to Safe2Tell
  • Decision to not re-open KP’s threat assessment case after being told he had an angry outburst in class and had a gun

The victim's parents wrote about the lack of intervention in an introduction to the report.

"The angry young man that murdered our daughter was a student in crisis who desperately needed guidance in a different direction from the one he pursued," wrote Michael and Desiree Davis. "The lesson to learn is not that our schools should be less tolerant and more punitive, rather that our schools are now, as never before, in a unique position to identify and secure help for troubled students."

The report quotes AHS Assistant Principal Darrell Meredith as saying, "We all carry some guilt" for the deadly shooting.

The report states that improvements have been made but more needs to be done to ensure student safety.

Read the full report here:


The report also makes several recommendations, among them:

  1. Principals, assistant principals, teachers, counselors, psychologists, coaches and School Resource Officers should consistently use a student information system to document matters of public safety concern, including student behavior concerns, conduct violations, intervention, academic concerns, threat assessment results and safety and support action plans.
  2. Schools and districts should promote Safe2Tell in formal trainings to students and staff each year.
  3. School districts should complete an Interagency Information Sharing Agreement with community agencies, including law enforcement agencies, mental health service providers, social service agencies and the criminal justice system.
  4. Schools and districts should install a validated threat assessment process, by either using the Virginia Student Threat Assessment Guidelines, a different validated process or by validating the current process with similar outcome measures to the Virginia plan.
  5. Schools and districts should install a validated risk assessment process and use the results to build a safety and support plan for any student who has a threat assessment.
  6. During the threat assessment, the Secret Service’s six principles and 11 questions should be used to gather and evaluate the early warning signs, threat factors, risk factors and protective factors. The process should emphasize an investigative, skeptical, inquisitive mind for each factor, until a clear yes or now is found.

Report co-author Sarah Goodrum of the University of Northern Colorado Department of Criminal Justice said the Safety Support Plan is critical.

"Counselors, psychologists and administrators should follow up regularly on how anger management is coming along, therapy, classes and academic progress," Goodrum said. "So that you don't just threat assess the student and then send them on their way, but instead, you build a support plan around that student to get them through the crisis."

LPS Superintendent Brian Ewert said he agrees with this report that warning signs were missed.

“My initial reaction to the findings is that there were warning signs,” he said in an emailed statement, “each in isolation and to some degree disconnected. The challenge was connecting the many isolated incidents into a significant threat.  The district and school failed to connect the dots.

Ewert said “LPS will own and learn from the missed opportunities we had to disrupt Karl Pierson's path to violence with effective interventions and countermeasures.  This will come from a much improved "systems-thinking" approach to information sharing, communication, and training, that includes district personnel, school personnel, law enforcement, external mental health professionals and agencies, and parents.”

Ewert said the district’s schools are safer now than they were two years ago.  He also said the Board of Education and administrators will be relentless in their pursuit of continuous improvement in the areas of safety and security…”

The Superintendent said there will be a special Board of Education meeting on Thursday at 4 p.m. with a press conference that will follow.

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