A source has provided another data set, this time following the smartphones of thousands of Trump supporters, rioters and passers-by in Washington, D.C., on January 6, as Donald Trump's political rally turned into a violent insurrection. At least five people died because of the riot at the Capitol. Key to bringing the mob to justice has been the event's digital detritus: location data, geotagged photos, facial recognition, surveillance cameras and crowdsourcing.