Trolling on social media: What does the law say?

Brenda Leyland, the 63-year-old woman accused of trolling the family of Madeleine McCann, has been found dead in a hotel.

Her body was found days after she was confronted outside her home by a Sky News reporter.

Mrs Leyland's Twitter account - which has been deleted - did not directly target the McCanns, who have "no significant presence" on social media.

Many of her messages had the hashtag #mccanns, making them easy to find.

One tweet read: "#mccann To Kate and Gerry, you will be hated by millions for the rest of your miserable, evil, conniving lives, have a nice day!"

Broadly speaking, trolling covers a variety of social media posts, from cheeky provocation, right through to abuse and violent threats.

Dr Arthur Cassidy, a psychologist who specialises in social media, said typically, trolls seek and enjoy a response from their victims.

He said Mrs Leyland's Twitter messages had been "unusual".

"Her whole repertoire of trolling is slightly different from those of well-seasoned trolls because of her uniqueness and the way she has done this," he said.

"It would signify to me that she has been quite a novice at this."

According to the Crown Prosecution Service, social media messages which "specifically target an individual or individuals and which may constitute harassment or stalking" could be a criminal offence.

Questions have come up about whether or not Mrs Leyland's messages could be considered to "specifically target" the McCann family.

Posts which also make a "credible threat of violence" against a person or property, may also be prosecuted.

There is also a possibility of "grossly offensive, indecent, obscene or false" messages also falling foul of the law.

People under the age of 18 are unlikely to be prosecuted as children "may not appreciate the potential harm and seriousness of their communications".

The CPS advises a "high threshold" for prosecuting social media users under the Malicious Communications Act 1988.

"Just because the content expressed in the communication is in bad taste, controversial or unpopular, and may cause offence to individuals or a specific community, this is not in itself sufficient reason to engage the criminal law," the guidelines add.

Posts must be more than "banter or humour" for prosecution to go ahead.

Last month Peter Nunn, 33, from Bristol, was sent to prison for 18 weeks after being found guilty of trolling Labour politician Stella Creasy over her campaign to put Jane Austen on the £10 note.

He sent what were viewed as "menacing" messages to the Walthamstow MP.

The judge also imposed a restraining order, preventing him from contacting either Ms Creasy or Caroline Criado-Perez, who began the Jane Austen campaign.

In 2011, Sean Duffy from Reading was also jailed for 18 weeks after he mocked dead children online.

Liam Stacey of Pontypridd was sentenced to 56 days in prison after he made racist remarks on Twitter about footballer Fabrice Muamba.

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