A police force said it had "learned lessons" after a High Court judge found it conducted no "real" investigation into the unexpected death of a 13-month-old girl for nine months.
Senior detectives in Cumbria thought a pathologist "may have jumped to conclusions" when she raised suspicions about the death of Poppi Worthington in December 2012.
They decided not to investigate until the full post-mortem report was ready but it was not finished until the following summer, according to a fact-finding family court judgment which was released for the first time today.
A host of failings by police before the parents of the Barrow-in-Furness toddler were arrested in August 2013 were identified last year by High Court judge Mr Justice Peter Jackson as part of care proceedings in relation to other children in the family.
In March 2014, Mr Justice Peter Jackson noted: "Due to the extreme delay in that process, there was no real investigation into P's (Poppi) death for nine months.
"Such minimal investigation as thereafter took place was inevitably affected by the delay and by actions not taken at an earlier stage."
Among the omissions were items not being preserved for forensic analysis either at the home or at the hospital after Poppi's collapse and the scene at the house not being secured.
The last used nappy believed to have been worn by Poppi was removed from the house by a relative with the knowledge of a police officer and placed in an outside bin - but was not found in a later search the same day.
Against national protocol no senior investigating officer immediately attended the home to ensure evidence was preserved properly, while no witness statements were taken until September 2013.
The eventual post-mortem report from Home Office pathologist Dr Alison Armour indicated the cause of Poppi's death was "unascertained" but raised concerns.
Poppi's father, Paul Worthington, 47, and her mother, who cannot be named for legal reasons, were later arrested, with Mr Worthington questioned on suspicion of sexually assaulting Poppi - an allegation he denies.
The 2014 family court hearing was told that Mr Worthington was informally interviewed by police in 1995 over his association with someone who may have committed offences against children.
In 2003 he was the subject of an unrelated allegation which was later retracted.
It also emerged that he watched pornography on his laptop in bed in the hours before his daughter's sudden death, which he described as "involving adults".
On admission to hospital and at post-mortem the youngster was found to have an earlier fracture of her right lower leg and suspected acute injuries in the region of the anus.
The main purpose of the hearing was to inquire into the causes and circumstances of these injuries, said Mr Justice Jackson in 2014.
Both parents denied causing any harm to their daughter.
In March, Cumbria Constabulary announced that no charges would be brought against anyone in connection with the youngster's death after prosecutors ruled there was "insufficient evidence" to provide a realistic prospect of conviction.
The force referred itself to the Independent Police Complaints Commission last summer and said three officers were subject to the investigation - with the suspension of one officer, who has since retired, while the two others had moved into different roles.
A police spokesman said: "Policies and procedures are continuing to be reviewed by the force and lessons have been learned from this case as we aim to ensure that Mr Justice Jackson's criticisms are addressed.
"The Constabulary are awaiting the outcome of the second Finding of Fact hearing with interest and will support any future inquest or hearing into this death."
Today's details emerged ahead of a review of medical evidence, starting in Liverpool today, which led to the judgment as Mr Justice Jackson ruled this month the time had come for "as much information as possible" to be placed in the public domain after submissions from a number of media organisations.
Further redactions to the partially released judgment were made after lawyers for the officially appointed Children's Guardian went to the Court of Appeal this week to argue that revealing of the information to the media could harm the interests of Poppi's siblings.
The full 2014 judgment, including the conclusions, will be published when Mr Justice Jackson reaches his findings from the present hearing at Liverpool Family Court.
Poppi's death was previously shrouded in mystery with the fact-finding judgment being kept private so as not to prejudice any criminal proceedings, while an inquest controversially took only seven minutes to declare her death as "unexplained".
In July, High Court judges ordered a fresh inquest after the first one held in Barrow last October was deemed ''irregular''.