Panorama investigates how survivors of major terror attacks are hounded and abused by conspiracy theorists who claim they are ‘crisis actors.' US conspiracist Alex Jones has just been ordered to pay nearly $1bn to families of the Sandy Hook school shooting after claiming the attack was a hoax. Now the BBC's disinformation correspondent Marianna Spring hunts the disaster trolls who target survivors of terror attacks in the UK and reveals new research about the popularity of these beliefs.