The mother of teacher Jane Longhurst - whose killer has been jailed for life for murder - is demanding the closure of some pornographic internet sites.
Liz Longhurst said her daughter was a beautiful person
Graham Coutts used websites depicting violent pornography to satisfy sexual fantasies, Lewis Crown Court had heard.
Liz Longhurst, 72, said such sites fed the "sick imaginations" of people like Coutts, who had denied Jane's murder.
But the Internet Watch Foundation said the sites were often based overseas and therefore not subject to UK laws.
Coutts strangled the 31-year-old teacher from Brighton with a pair of tights in March 2003 and then kept her body in a storage unit for over a month.
During the trial, the prosecution said Coutts had downloaded images of necrophilia and asphyxiation and had "acted out for real on the unfortunate Jane Longhurst the fantasies that he had filed on his computer".
Mrs Longhurst, who sat in court for all 13 days of the trial, said: "I feel pressure should be brought to bear on internet service providers to close down or filter out these pornographic sites which have played such a prominent part in this trial, so that people like Jane's killer may no longer feed their sick imaginations and do harm to others.
"I realise political pressure will have to be applied to bring about these changes but I understand that there are some MPs interested in that."
Jane Longhurst's body was found five weeks after she disappeared
But the IWF said that the laws governing adult content on websites differed around the world.
"Legislation over internet content comes under the jurisdiction of the country of source, therefore the IWF and UK law enforcement agencies can only control material hosted in the UK," a spokeswoman said.
The situation was different for child abuse images which were globally thought to be unacceptable and covered by international guidelines, she said.
"If the websites cited in this specific case were hosted in the UK, we would have referred them to the UK police for further investigation under the Obscene Publications Act," she added.
BBC News Online technology correspondent Mark Ward agreed it would be almost impossible to stop such sites.
"The problem is that even if you can get one ISP to take a site down, there is so much competition to host sites around the world that it will probably appear on another before long," he said.