A Study of the Pre-attack Behaviors of Active Shooters in the United States Between 2000 and 2013

Excerpt:  “In the weeks and months before an attack, many active shooters engage in behaviors that may signal impending violence. While some of these behaviors are intentionally concealed, others are observable and — if recognized and reported — may lead to a disruption prior to an attack. Unfortunately, well-meaning bystanders (often friends and family members of the active shooter) may struggle to appropriately categorize the observed behavior as malevolent. They may even resist taking action to report for fear of erroneously labeling a friend or family member as a potential killer. Once reported to law enforcement, those in authority may also struggle to decide how best to assess and intervene, particularly if no crime has yet been committed.”