The killing of right-wing activist Charlie Kirk on Wednesday at a college in Utah is the latest in a string of acts of political violence in recent years that have spanned the political spectrum.

Political violence is hardly unprecedented in the United States. In fact, the country has “a long, dark history” of violence that has “struck the highest level of American politics,” said Kevin Boyle, a Northwestern University historian.

Utah Gov. Spencer Cox said that a family member of the suspect's reached out to a family friend who contacted the Washington County Sheriff's Office.

Why political violence has spiked in recent years and what can be done to stop it - US is experiencing most profound surge in political violence since the 1970s, data shows

Distinguishing madmen and militants is never simple, but the Prosecution Project, led by Michael Loadenthal of the University of Cincinnati, analyses felony criminal cases involving political violence to see which ideologies are most common.