The body of the shy British teen was found on a remote farm in October with her arms bound and duct tape covering her mouth. The girl had been raped and murdered by someone she met on Facebook.
"If you're an overweight girl living in England and doesn't have someone to love her, you will look for that and you will grab at that, and the predators know that," said Parry Aftab, executive director of Wired Safety, a leading Internet safety Web site.
Peter Chapman, a 33-year-old convicted rapist, was arrested after Hall's death on an unrelated charge and confessed to Ashleigh's murder.
"I killed somebody last night," Chapman told police. "I need to tell someone from CID where the body is."
Chapman posed online as a handsome teenage boy, befriended Ashleigh on Facebook and other Web sites and sent her flattering messages, telling her she was "sexy as hell." Eventually, they arranged to meet.
Ashleigh told her mother she was attending a sleepover, according to the Telegraph, but instead went to meet Chapman, who said he raped and suffocated her in his car, and then dumped her body in a field.
The murder prompted the famously opinionated British press to call for action. Britain's Child Exploitation and Online Protection Centre, CEOPS -- an organization dedicated to eradicating all forms of child sexual abuse -- claimed that in the first quarter of the year it received 253 complaints about Facebook; 39 percent of them were suspected cases of kids being groomed online by pedophiles.
In December, Facebook, the world's most popular social networking site, created a Global Safety Advisory Board to tackle issues such as online stalking and cyber-bullying among its 400 million users.
Serious crimes are rare, but when they happen, they capture headlines. Last year, a British man dubbed the "Facebook Murderer" trawled the Internet searching for victims, according to police.
Last month, 25-year-old Paul Bristol was jailed for murdering his ex-girlfriend after seeing a photograph of her on Facebook with another man.
A nursery worker in southern England recently pled guilty to photographing horrific acts of abuse she carried out on children in her care and sending the images to a man and a woman she met on Facebook and other social networking sites.