Detectives have said there is a "very real chance" the killer of a young woman who was murdered in 1986 is still at large after a man wrongfully convicted of the frenzied sexual attack was freed.
Peter Sullivan spent the last 38 years behind bars for murdering 21-year-old Diane Sindall in Birkenhead, Merseyside, before he was acquitted at the Court of Appeal on Tuesday.
Now 68, Mr Sullivan was released from prison after judges heard a DNA profile pointing to an unknown attacker was found after new testing on semen samples preserved from the crime scene.
Merseyside Police said more than 260 men identified in the original investigation had been tested and eliminated as suspects.
The force's head of investigations, Det Ch Supt Karen Jaundrill, said officers "had not met with any resistance" to DNA screening.
She has now appealed for people in the community to come forward if they can think of anyone whose "behaviour they were not happy with" at the time, admitting there was a "very real chance" the killer was still at large.
- Who is Peter Sullivan and why was he jailed?
- Why was Peter Sullivan not freed earlier?
Miss Sindall was dragged into an alley and beaten to death on 2 August 1986 in an attack detectives described at the time as the worst they had ever been involved in.
Merseyside Police said it had immediately reopened Miss Sindall's case after being told there was a new DNA profile in 2023, despite Mr Sullivan's appeal still being in progress at the time.
Det Ch Supt Jaundrill said that while the DNA was the main focus of investigative efforts, her team will rely heavily on people who lived in Birkenhead at the time for answers.
"I'm really hopeful with the work that we are doing but we really are relying on the community, particularly Birkenhead, just to really think about the nature of that investigation at the time," she said.
"Try and reflect on any individuals that you weren't happy with at the time.
"It may be that somebody has passed away and you weren't happy with their behaviour at the time and you think they were linked.
"My ask would be please contact us, regardless of how insignificant you think the information is, and let us judge where that fits into our investigation."
Miss Sindall, who worked as a florist, had also been doing part-time bar work at the Wellington Pub in Bebington to save up for her upcoming wedding to her fiancé, David Beattie.
She began driving to her home in Seacombe in her blue Fiat van but seemingly ran out of petrol, and began walking to what police believe was either a bus stop or an all-night garage shortly after 00:00 BST.
Her semi-naked body was discovered partially concealed in an alleyway by a woman walking her dog at about 12:30 that day.
The victim had suffered severe injuries and her death was found to have been caused by repeated blows to the head.
Det Ch Supt Jaundrill said Miss Sindall's family and fiancé were "fully supportive" of the new investigation and "very much want us" to find her real killer.
Asked about the chances of the young woman's attacker still being on the streets nearly four decades later, she added: "There is a very real chance.
"That's where I reiterate our dedicated team of investigators are working tirelessly.
"We're exploiting every opportunity to try and identify who the person is in relation to that DNA sample, but it does come back to that point – we are reliant on the communities, particularly [in] Birkenhead, to provide information."
The force has defended how it investigated the original case, and highlighted that the technology to extract a DNA profile from the semen samples recovered from Miss Sindall's body was still many years away at the time of her murder.
It has also pointed to the fact that two other grounds of appeal, related to how Mr Sullivan was interrogated and the admissibility of bite mark evidence, were rejected by appeal court judges.
Det Ch Supt Jaundrill said: "Nobody at Merseyside Police underestimates the impact on Peter Sullivan and I am grateful that the outcome at court will allow him to go out and rebuild his life.
"Our focus remains on finding justice for Diane."
Mr Sullivan's solicitor Sarah Myatt said her client was a "private man" and wanted to be "left in peace" to rebuild his life.
Mr Sullivan, in a statement read to the media by Ms Myatt outside the Court of Appeal, said he was not "angry or bitter" and expressed his wish that the Sindall family get justice.
Ms Myatt, who has represented him for 20 years, said she had been "honoured" to read those words on his behalf.
"The comments he made about wanting the family to get a resolution, to find peace, that is a true reflection on the man that he is," she said.
Another man who spent time in prison for a crime he did not commit, John Actie, said he could not understand why Mr Sullivan was not angry about everything he had gone through.
While on remand, Mr Actie was in jail for two years while accused of the murder of Lynette White in a Cardiff flat on 14 February 1988.
He was cleared at trial.
Three of his co-defendants were found guilty of her murder, but later had their convictions quashed by the Court of Appeal in a case that garnered national attention and became known as the Cardiff Five in the media.
Mr Actie told BBC Radio Wales: "It just made my stomach go over. It could have happened to us, we could have been in jail for a lot longer.
"Fortunately we were lucky and we got out because they came to the right decision.
"He's not bitter? Well I'm bitter, and I spent two years in jail. I have nightmares about it still.
"He's got to start his life again now, at 68. It's absolutely terrible.
"I'm flabbergasted that he's not angry with what's happened to him – I just can't believe that he's not angry. I'm choking up thinking about it."
