A UK man has been jailed for 18 weeks after trolling pages set up on social networks for girls who have died. 

Sean Duffy, of Reading, Berkshire, posted negative comments on social networking site pages in remembrance of girls who have died, such as Worcester teenager Natasha MacBryde who killed herself by throwing her body under a train due to bullying reports the BBC. 

Duffy targeted the bereaved relatives of the deceased, which were people he did not know. Duffy would send hurtful emails or post provocative posts on sites like Facebook and YouTube in hopes of prompting emotionally loaded responses. 

In MacBryde's case, he called her a "slut" in one of his posts. He also posted a video on YouTube called "Tasha the Tank Engine," which depicted the children's character Thomas the Tank Engine with MacBryde's face on it. 

Duffy pleaded guilty on two counts of sending a communication of an offensive or indecent nature. The charges were related to the Facebook and YouTube posts about MacBryde. Duffy has been jailed for 18 weeks. 

The case places a spotlight on cyberbullying and trolling, which have become increasingly problematic in recent years as social networks and other electronic communication mediums become more widely used. 

"People feel protected by anonymity and the true nature of people comes to the fore," said Fevzi Turkalp, a technology expert from gadgetdetective.com. "Someone will go onto an Apple website and say something derogatory about Apple, knowing full well people on there will be fans of Apple, in order to provoke a response."

"Misuse of Internet sites can destroy teachers' confidence and professional reputation and provide yet another vehicle for false allegations against staff," added Chris Keates, General Security of the NASUWT teacher's union. "New cases of abuse, harassment and humiliation are emerging all the time."

Duffy never knew MacBryde or her family.