Police have made a fresh appeal for information after a coroner recorded a verdict of unlawful killing over the death of a 19-month-old girl.
Shauna Pritchard suffered a "horrifying list of injuries" which included three instances of fractures to her spine, an inquest heard.
The toddler, from Blacon, near Chester, also suffered traumatic head injuries which ultimately led to her death.
Cheshire Police said the inquest, before Coroner Nicholas Rheinberg, heard that Shauna was living with her mother, Toni Marie Wright, 29, and her partner Damien John Price, 24, before she died.
The toddler would spend each Sunday with her father, Clinton Pritchard, 29.
On the night of April 20, 2004, the inquest was told, Wright, originally from Wrexham, left the family home to visit a late-night chemist because Shauna had been ill with vomiting, diarrhoea and listlessness.
She returned to be met by Price who told her Shauna was not breathing.
The toddler was rushed to the Countess of Chester Hospital, where she was initially treated, and then taken to Alder Hey Children’s Hospital in Liverpool, where she later died.
Mr Rheinberg, sitting on Thursday and Friday last week, took evidence from 10 medical experts and paediatricians about Shauna’s injuries.
As well as the fractures to her spine, she had haemorrhaging behind the eyes and retinal separation, and old and new cases of bleeding on the brain.
There was also bruising on her head, neck, and abdomen, the inquest heard.
Mr Rheinberg was told the force used to cause the injuries to Shauna was equivalent to a fall from a second-floor window.
Cheshire Police said Shauna’s mother declined to answer the coroner’s questions and Price told the hearing he could not explain how the child sustained the injuries.
Mr Rheinberg said that, in the context of "very compelling evidence" from medical experts, there could be no doubt that Shauna was unlawfully killed, and that the cause of death given - traumatic head injuries - "hides a whole catalogue of abuse".
Following Shauna’s death, two people, thought to be Wright and Price, were arrested on suspicion of murder.
A Cheshire Police spokeswoman said: "Following Shauna’s death, a 24-year-old woman and a 21-year-old man were arrested on suspicion of her murder.
"They were later released without charge following advice from CPS.
"Nobody has ever been convicted in relation to Shauna’s death."
Detective Inspector Mark Tasker, of Cheshire Police’s Strategic Public Protection Unit (SPPU), is leading the inquiry into Shauna’s death.
He said today: "Extensive investigations have already taken place into the circumstances surrounding Shauna’s death, and every effort has been made to identify and bring to justice the person or persons responsible for Shauna’s death.
"We have worked very closely with colleagues from other agencies and the Crown Prosecution Service.
"Presently the inquiry team have explored all available investigative opportunities.
"Any new information which comes to light will be thoroughly pursued."
He added: "Now is the time for anyone with any relevant information, no matter how trivial it may appear, to come forward and speak with police.
"We must never forget that a 19-month-old baby girl has lost her life.
"This file will remain open until the person, or persons, responsible for Shauna’s death are brought to justice."
Anyone with any information is asked to contact Mr Tasker on 0845 458 0000 or call Crimestoppers, anonymously, on 0800 555 111.