It was one of the worst school shootings in American history, but some people insist that the Sandy Hook massacre never happened. They post YouTube videos and spread rumours online, and their false theories have been repeated by a media mogul conspiracy theorist who has been linked to Donald Trump. Now, after years of harassment, the families of the victims are fighting back online. Lenny Pozner clicks on a YouTube video showing his street and the outside of his home. The camera zooms in on his balcony, and his address and a route to his door flash up on the screen.