Online social media and emerging methods of electronic communication are changing how people communicate and interact with world around them. Increasingly, those contemplating engaging acts of spree violence express themselves in online social media. It is important that investigators, analysts, and those responsible for school, workplace, and public safety understand how this behavior plays a key role in predicting and interdicting the violence. Items of evidentiary value can now often be recovered from online communities. This evidence can provide indicators of planned violence and help to shed light on the thought processes and motivations that led to the tipping point of violence. The training will explore the interaction between social media and spree violence through a historical examination of case studies ranging in time from 1927 to 2022. Police, prosecutors, probation officers, school and university administrators, and others responsible for workplace and public safety can all benefit from this training.