Detectives investigating the murder of a Sheffield mum 20 years ago believe the key to cracking the case lies in the community where the victim lived.
Patricia Grainger, aged 25, was stabbed, sexually assaulted and strangled before her body was dumped under a bed base in a brook running through the Parson Cross estate.
Her body was found by two teenage boys 20 years ago today but her killer has never been caught.
Three arrests have been made over the years but nobody has ever been charged.
Today a mobile police station has been set up outside a parade of shops on Buchanan Road, Parson Cross, close to where Patricia lived.
Detectives hope members of the public come forward with information which could solve the murder mystery.
Detective Chief Inspector Dave Stopford, who is leading the police probe, said local knowledge could be the key to the case.
"Virtually everything we have had over the last 20 years in terms of information has come from the Parson Cross " he said.
"It is a community where a lot of people live for their entire lives and I am confident that if there is an answer to be had it will be in the Parson Cross community."
He said detectives were missing 'that vital piece of evidence' which could nail the killer and he urged people who know the culprit or have suspicions to come forward.
"It would be fantastic if someone came forward saying they had witnessed something but it is more likely that over the last 20 years the person responsible has spoken to other people, or perhaps people had suspicions at the time but for whatever reason did not come forward.
"We know from previous cases that it is a burden for offenders to carry something like this for such a long time and that people to confide in others who may have been close to them at that time. But loyalties do change and relationships change and that is what I am hopeful of - that a conversation like this has taken place and that people come forward."
He described the murder as 'a terrible offence'.
"Patricia was an innocent woman with learning difficulties, she was a vulnerable person. It was a terrible offence," he added
"She was stabbed a number of times and there was evidence of strangulation. She was also submerged in water when she was found.
"This is a live investigation. We are still following up lines of enquiry and we have a major incident review team reviewing all historic murders. They are all important to us.
"The impact on Patricia's son, Danny, and the family is still clear to see today and they are desperate to find out who has done this, as are we."
Anyone with information should call South Yorkshire Police on 101.