A Berkshire man has been jailed for posting abusive messages online about a schoolgirl after she committed suicide.
Sean Duffy, 25, of Reading, was handed an 18-week sentence for posts on social networking sites about Worcestershire teenager Natasha MacBryde.
He previously pleaded guilty at Reading Magistrates' Court to sending indecent or offensive communications.
Police said Duffy also posted abuse about dead teenagers in Northumberland, Gloucestershire and Staffordshire.
Duffy, of Grovelands Road, admitted two offences of "trolling" a term used to describe the trend of anonymously seeking to provoke outrage by posting insults and abuse online.
They related to Facebook and YouTube posts about Miss MacBryde, 15, from Bromsgrove, who Duffy had never met.
He was traced by police through information from his internet service provider and arrested.
Miss MacBryde had thrown herself under a train in February after being bullied.
Duffy subsequently posted anonymous messages on a remembrance page - "Monday 14th February will always be remembered as Tasha MacBryde day" - set up by her 17-year-old brother James to allow friends and family to pay their respects to the teenager.
In one of the posts he called her a slut. He also posted a video on YouTube, entitled Tasha the Tank Engine, showing the children's character Thomas the Tank Engine with Miss MacBryde's face.
Jo Belsey, prosecuting, said the family were "understandably outraged, disgusted and hurt".
In a statement read to the court, her father Andrew MacBryde said he "could not believe anyone could stoop to such depths" after his son told him of the online posts.
He added that Duffy's actions had "added to the horror of dealing with the death of their beautiful daughter".
The magistrates were also asked to consider three other cases when sentencing Duffy, who the court heard suffers with alcohol problems and has Asperger's syndrome.
He had also posted offensive messages about Lauren Drew, 14, of Gloucestershire, who was found dead after suffering a suspected epileptic seizure, Hayley Bates, 16, of Staffordshire, who died in a car crash, and Jordan Cooper, 14, who was stabbed to death in Northumberland.
On Mother's Day he posted a message on an online memorial page to Lauren reading: "Help me mummy, it's hot in hell".
Duffy also produced an image of Hayley with crosses on her eyes and red marks on her face. He also wrote explicit messages to Hayley's sister Heather.
The family of stabbing victim Jordan had also seen abusive messages directed at the youngster on an online memorial and a YouTube video defacing an image of the teenager.
Magistrates also gave Duffy an Asbo, banning him from using social networking sites for five years.
Outside court, Lauren's father Mark Drew said: "Lauren didn't deserve this.
"Seeing him in court was really hard. I was so angry.
"Lauren was my only daughter and I worshipped the ground she walked on.
"This person hid behind the computer screen with no feeling."
Mr Drew urged Facebook to do more to prevent the website being misused, adding that it was "a wonderful thing if used right".
Carol Gelder, Lauren's mother, told the BBC: "It was quite frustrating because we couldn't stop it. We didn't know how to stop this person.
"With the pain we were going through anyway we didn't anticipate that we'd have to deal with this as well.
"I remember going up lying next to her and just crying and thinking I can't protect her from this."
Lance Whiteford, mitigating, said Duffy had been diagnosed with Asperger's syndrome at an early age and one of the characteristics was an inability to judge the reaction of others.
He said Duffy had also struggled with alcohol problems and lived "a miserable existence".
Duffy had no previous convictions but had received one caution for a similar offence.
Paul Warren, chairman of the magistrates' bench, said: "This case serves to illustrate the harm and damage done by the malicious misuse of social networking sites."
Sherry Adhami, of the charity Beatbullying, said: "Today's ruling is a monumental move towards bullying and cyberbullying being taken more seriously and sends a strong message to society that bullying, whether online or offline, is not going to be tolerated.
"It's time that stopping bullying at the source is placed higher on the government's agenda."