Donald Trump’s second impeachment trial began with a haunting video. Representative Jamie Raskin, the lead impeachment manager, screened a compilation of clips gathered from the Washington D.C. riots in January, tracing the mob’s route down Pennsylvania Avenue and documenting how its members smashed their way into the Capitol building. 

The footage was filled with violence, obscenities and disturbing images of an enraged crowd. The video was compiled from a variety of sources, including clips posted to social media by the rioters themselves. It played to a hushed chamber. When it had finished, Raskin said: “You ask what a high crime and misdemeanor is under our constitution? That’s a high crime and misdemeanor.”

Although Trump was acquitted by the Senate, evidence gathered from social media played a central role in the case for impeachment. “There were countless social media posts, news stories, and, most importantly, credible reports from the FBI and Capitol Police that the thousands gathering for the president's Save America March were violent, organized with weapons and were targeting the Capitol,” said Raskin on Wednesday. “As they would later scream in these halls and as they posted on forums before the attack, they were sent here by the president.”

The storming of the U.S. Capitol was one of the most extensively and closely documented events in modern history. Around the world, people watched the violence unfold in real time, via livestreams, selfies and social media posts. Rioters uploaded videos and commentary of themselves entering the building. But as quickly as the evidence was shared, it began to disappear. Within hours, a call went out from the online investigation platform Bellingcat: Save everything you can, while you can.