Australian police said on Monday that social media site Facebook had refused to take down a page containing offensive material about the man accused of murdering Irish woman Jill Meagher.
The search for Meagher, 29, who vanished while walking home from a Melbourne bar earlier this month, sparked a huge social media campaign, with more than 122,000 people "liking" a Facebook page dedicated to the case.
But several hate pages sprung up after Meagher's body was found in a shallow roadside grave 50 kilometres (31 miles) northwest of Melbourne and Adrian Ernest Bayley, 41, was charged with her rape and murder.
Meagher's husband and the police have urged the public to refrain from commenting on Bayley or the highly publicised case, warning that any remarks made on social media sites had the potential to prejudice his trial.
Chief Victoria state police commissioner Ken Lay said Facebook had been approached about taking down one page in particular which contained offensive material about Bayley.
"Now, they've refused to do that," Lay told commercial radio.
"We've all got a social responsibility. Facebook is part of our community and I would have thought that it would have only been reasonable," he added.
"We've got to remember that no matter how horrible this crime is, this gentleman has got to be afforded a fair trial. It's not for Facebook pages or anyone else to be taking justice into their own hands."
Facebook was not immediately available for comment.
Lay said social media had been "enormously helpful" in the investigation of Meagher's disappearance, with thousands of people flooding the "Help us find Jill Meagher" Facebook site with information.
But he said there had also been drawbacks and some of the online "hatred" incited against Bayley was not helpful, with police seeking further advice on the issue.
Meagher's disappearance during the short walk home struck a nerve in Melbourne, where an estimated 30,000 people turned out for a peaceful anti-violence march on Sunday through the suburb where she was last seen alive.