Documents By Type:
Overviews and comparisons
Education: Failures and Family Involvement (version 1.10) [13 pp, 116 Kb]

This document provides brief summaries of the shooters’ negative experiences in educational settings, including academic failures, disciplinary actions, and other issues. It also notes their families’ involvement in education, primarily as school personnel such as teachers or professors. Finally, it identifies those cases in which the shooters targeted specific people at school due to perceived injustices, as well as those shooters whose violence may have been related to their family members’ positions or accomplishments in education. 

A Guide to Insider References Used by School Shooters and Other Attackers [7 pp, 455 Kb]

This document lists nicknames, usernames, quotations, and other items that may be used by potential attackers to refer to previous killers or incidents of violence. Knowing these references is important to anyone conducting threat assessments. For examples of cases in which shooters used such insider references prior to their attacks, see the companion document “Reading Between the Lines: Recognizing Insider References to School Shootings.”

Intended and Targeted Victims (version 2.18) [6 pp, 82 Kb]

One way to make sense of school shootings is to examine who the targets were. Though some attacks consisted of indiscriminate violence against anyone in the vicinity, others were partly or completely targeted against specific people. This document lists shooters and notes their targeted victims in five categories: bullies, rivals, family members, girls/women, and school personnel.

Legal Histories of School Shooters (version 1.3) [3 pp, 43 Kb]

This document lists arrests, law enforcement contacts, and reports to the police about the perpetrators of school shootings that occurred prior to their attacks. 

The Origins of Firearms Used in School Shootings in the United States (version 1.1) [5 pp, 477 Kb]

This document identifies the sources of firearms used in 52 school shootings (involving 54 perpetrators) during the twenty-five years from 1991 through 2015. The sample includes both single-victim and multi-victim shootings committed by secondary school, college, and aberrant adult perpetrators. 

Patterns Among School Shooters: Body-Related Issues and the Military (version 1.28) [11 pp, 145 Kb]

This document presents data in several areas: body-related issues that may have been challenges to the perpetrators’ identities, family members who served in the military and/or law enforcement, the shooters’ aspirations to serve in these professions, and the frequent thwarting of these aspirations. These different sets of data are presented together to explore possible connections between the shooters’ family role models for masculinity, their own possible sense of damaged manhood, and their own striving to be soldiers or police officers. Note: though the focus is on masculine identity, the document also includes female shooters with body-related issues, family members in the military, and military aspirations.

Role Models, Contagions, and Copycats: An Exploration of the Influence of Prior Killers on Subsequent Attacks (version 3.2) [18 pp, 542 Kb]

This is an exploration of the issue of influence among school shooters, documenting references by subsequent attackers to those who came before them. It also notes historical figures who may have served as role models for violence. The bulk of the document is a listing of school shooters and their influences, including a diagram of the lines of influence from Columbine through subsequent attacks. For an analysis of the multiple types of influence among school shooters, see the document “Different Types of Role Model Influence and Fame Seeking Among Mass Killers and Copycat Offenders.” For a graphic representation of the influence of Columbine on subsequent attacks, see “The Influence of Columbine” (poster and tabloid format).

School Shooters: A Miscellany (version 1.35) [8 pp, 469 Kb]

This document pulls together information on a variety of issues relating to school shooters, including adoption, immigration, fire-setting, marriage, self-injurious behavior, hostage situations, attempts to escape, Nazi interest, satanism, suicide by cop, those who killed family members, and those who have been released from prison. It also covers multiple aspects of sexuality. 

School Shooters: The Myth of the Stable Home (version 1.15) [6 pp, 73 Kb]

A common misconception about school shooters is that they are typically kids from stable, middle-class families. This document presents information on the families of shooters, including factors such as divorce, domestic violence, child abuse, criminal behavior, and parental alcoholism and drug addiction. The percentage of broken homes and dysfunctional familes is very high.

School Shootings: Fast Facts (version 1.2) [1 p, 423 Kb]

This document answers frequently asked questions about school shootings, with links to other resources that provide more comprehensive information.

Shooter Info: Complete Spreadsheet [48 Kb]

This is the complete spreadsheet that lists all attributes of all shooters profiled on this site. This document is continually updated to reflect new information, and the data should be identical to those in the School Shooters .info database. Latest revision: 10 November 2023. Note: This is an Excel file. It will download to your computer, not open in your browser. Once it’s downloaded, you can manipulate the rows and columns as with any spreadsheet. Thus, you can rank or organize the shooters by date of attack, age, psychological type, number of victims, or any other variable included in the data.

Tally of Shooters’ Use of Psychiatric Medications and Substance Abuse (version 1.3) [4 pp, 467 Kb]

This document summarizes the medication and substance abuse histories of dozens of school shooters. This is a companion document to the article “Psychiatric Medications and School Shootings.”

A Timeline of School Shootings (version 1.41) [6 pp, 213 Kb]

This is a timeline of all the school shootings and other attacks included on this site.

Nikolas Cruz · Marjory Stoneman Douglas High School
Cruz Cell Phone Content and Internet Searches [35 pp, 2.76 Mb]

This is a presentation of the Marjory Stoneman Douglas Public Safety Commission, compiled by Special Agents Randy Camp, Chuck Massucci, and John Seuss.

Shooting at Marjory Stoneman Douglas High School [64 pp, 10.39 Mb]

This is a presentation of the Marjory Stoneman Douglas Public Safety Commission, compiled by Pinellas County Sheriff Bob Gualtieri.

Unreported Information Showing Nikolas Cruz’s Troubling Behavior [69 pp, 1.65 Mb]

This was compiled by the Marjory Stoneman Douglas Public Safety Commission.

Eric Harris / Dylan Klebold · Columbine High School
11,000 Page Report

These two documents were found online, compiled by an unknown researcher. I have attempted to obtain permission from the researcher to post this material, but have been unsuccessful. I am posting the documents here to preserve this meticulous work. These two documents provide a page-by-page listing of the contents of the first 11,000 pages of JCSO documents.

Pages 1-5,500 [14 pp, 132 Kb]
11,000 Page Report
Pages 5,501-10,937 [17 pp, 143 Kb]
The Influence of Columbine

This diagram portrays the apparent lines of influence from Columbine through subsequent attacks. All of the post-Columbine perpetrators included here either explicitly cited Columbine as an influence or made oral or written references that suggest it influenced their own attacks. The lines of influence illustrate links between those who were influenced by Columbine and later perpetrators whom they influenced in turn. The New York Times described an earlier version of this document: “Langman has created a mass-shooter diagram tracking the influence Columbine has had on more than 30 other rampage attacks at schools and elsewhere, from California to Germany. The diagram resembles a corporate flowchart, with lines branching out and intersecting, but all of them flowing out of two names: the Columbine killers.” This document may be downloaded as a large-scale poster or in smaller tabloid format. This is a companion document to “Role Models, Contagions, and Copycats: An Exploration of the Influence of Prior Killers on Subsequent Attacks.”

The Influence of Columbine (poster format) (version 1.4) [1 p, 411 Kb]

This large-format poster shows all attacks influenced by Columbine, arranged in a timeline format, with attack details and lines of influence.

The Influence of Columbine
The Influence of Columbine (tabloid format) (version 1.3) [1 p, 409 Kb]

This 11-by-17-inch version of the diagram features a compact representation of the lines of influence between perpetrators.

JCSO Columbine Documents Indexed by Name [56 pp, 281 Kb]

This document is an index to thousands of pages of documents compiled by the Jefferson County Sheriff’s Office (JCSO) related to the attack at Columbine High School. This is a guide to summaries of hundreds of interviews organized first by the first name of the interviewee and then by the last name of the interviewee. The original document was found online with no indication of who created it. It has been redesigned for this site.

JCSO Columbine Documents Organized by Theme (version 1.6) [25 pp, 229 Kb]

The attack at Columbine generated over 27,000 pages of documents for the Jefferson County Sheriff’s Office (JCSO), most of which have been made public. These include reports from thousands of interviews with people who knew Harris and Klebold, as well as the killers' personal journals, school planners, academic assignments, yearbook inscriptions, and more. I have organized an index to assist people in locating references by theme. For example, there are pages listing references to Harris and Klebold being harassed, as well as references to Harris and Klebold not being harassed, and references to Harris and Klebold harassing others. There are 10 categories divided into additional subcategories.

Adam Lanza · Sandy Hook Elementary School
Adam Lanza: Timeline [34 pp, 894 Kb]

This document chronicles Adam Lanza’s life and noteworthy activities leading up to the Sandy Hook shooting. Version 2.0 has been greatly expanded. (Special thanks to Reed Coleman.)

Evan Ramsey · Bethel High School
Court Cases in the Ramsey Family (version 1.4) [4 pp, 452 Kb]

Evan Ramsey’s family had frequent contact with the legal system in Alaska. This document contains a summary of the court cases that he and his family were involved in.

Jeffrey Weise · Red Lake High School
Jeffrey Weise: Timeline [4 pp, 445 Kb]

Because there is no book or article that tells Weise's life story in a comprehensive way, I have pieced together facts about him and his family from a variety of sources.

Aaron Ybarra · Seattle Pacific University
Aaron Ybarra: Family Tree [1 p, 31 Kb]