Social media experts say it is natural that people who use sites such as Facebook or MySpace as a major form of communication should turn to these sites with personal tragedies.
These memorial sites often attract thousands of friends and well-wishers, as in the case of the pages set up after the deaths this month of Elliott Fletcher, 12, and Trinity Bates, 8.
Students from Brisbane College in the state of Queensland flocked to a memorial site set up after Fletcher was stabbed in a schoolyard fight two weeks ago, but it was defaced with offensive comments and images including child pornography and bestiality.
The same happened to a site set up in memory of Bates who was taken from her bed in Bundaberg, Queensland, with her body found in a nearby storm drain on Monday. A teenager accused of her murder was also revealed to be a Facebook friend of her parents.
Queensland Premier Anna Bligh has appealed to the owners of U.S.-based Facebook to find ways to stop a recurrence of these types of "sickening incidents."
"To have these things happen to Facebook pages set up for the sole purpose of helping these communities pay tribute to young lives lost in the most horrible ways adds to the grief already being experienced," Bligh wrote in a letter to Facebook founder and CEO Mark Zuckerberg which was released to the media.
"I seek your advice about whether Facebook can do anything to prevent a recurrence of these types of sickening incidents."
A spokesman for Bligh said the premier had yet to receive a response from Zuckerberg.
But Facebook spokeswoman Debbie Frost said the site had rules to check content and reviewers were quick to respond to any reports of hate or threats against an individual, pornography, or violent photos or videos, and would remove the content, and either warn or disable the accounts of those responsible.
"Facebook is highly self-regulating, and users can and do report content that they find questionable or offensive," Frost said in a statement.
She said in the tragic case of Elliott Fletcher, Facebook responded to reports of vandalism from others users and the police by removing the groups and disabling the accounts of the people responsible but that was about all the action possible.
"It is simply not possible to 'prevent' a person with a sinister agenda from undertaking offensive activity anywhere on the Internet where people can post content. Nor is it really possible in real life," Frost added.
Detective Superintendent Peter Crawford of Queensland police said people should think twice before setting up such social networking groups. As well as memorial sites, Facebook pages popped up vilifying the man accused of murdering Bates.
"I would say anybody thinking about putting these sites up in the future need to realize that they're going to attract these kinds of people," Crawford told radio station Fairfax Radio 4BC.
"The reality is once you open these sites up to open access to anyone on the Internet, you are going to attract unsavory people and clearly that's occurred again."