A woman who launched a petition opposing the possible release of a child murderer says she has had a "phenomenal" response.
Colin Pitchfork was the first person to be convicted using DNA profiling for killing Leicestershire schoolgirls Lynda Mann and Dawn Ashworth, both 15.
The Parole Board will review his case in September as he nears the end of a 28-year minimum term on his sentence.
Lynda's sister, Rebecca Eastwood, has now gathered almost 16,000 signatures.
Ms Eastwood, from Liverpool, was two years old when her sister was murdered by Pitchfork in 1983.
She said: "It's really difficult having to relive the stories and see his picture on the petition, but I think the sadness and anger is bringing a determination to get this petition done and hopefully win our fight to keep him where he is."
More than 13,200 people have signed the online petition with a further 2,500 signatures collected on paper.
Pitchfork, now 55, was jailed for life in 1988 after he admitted two charges of murder, two of rape, two of indecent assault and one offence of conspiracy to pervert the course of justice.
Lynda was killed in Narborough in 1983 while Dawn, from Enderby, was murdered three years later.
The Parole Board said he had made progress in prison and could either be released or transferred to an open prison later this year.
"I have heard he has a glowing record and has never been on report while he's been in prison, but it's not very hard to be well behaved when you are locked up," said Ms Eastwood.
"I do think he's a threat to the public and I don't think what he's done could ever be fixed. He's a very calculating killer and he shouldn't be free."
Mrs Eastwood is hoping to send the petition to the Parole Board along with statements from the families of Pitchfork's victims.