Richard Bacon's search for cyber trolls
Broadcaster Richard Bacon is one of an increasing number of victims of cyber bullies and internet trolls, using fake identities on social networking sites to torment, harass and abuse.
They even targeted the tribute sites of young people who have taken their own life, posting vile comments and images with devastating consequences for the victims' families.
He discusses what motivates internet trolls with psychologist Dr Emma Short.
Find out more in The Anti-Social Network on Monday 19 March at 2100 GMT on BBC Three.