President Donald Trump has appeared on the Fox News morning show, Fox & Friends, where he announced that he believed Mr Kirk’s murderer had been taken into custody.

A presidential historian compared today's political violence to the 1960s assassinations, warning that social media has created a more dangerous landscape for democracy.

The arrest of Tyler Robinson, the 22-year-old Utah native who on Friday night was expected to be charged with the murder of conservative activist Charlie Kirk, bookends the latest episode of extraordinary American political violence. But an atmosphere of fear and fragility continues to dominate political discourse across the country.

Political violence has targeted the political left and right and has been perpetrated by the left and the right. Here's a recap since 2011.