A six-week-old baby was killed by her mother after she stuffed pages from the Bible into the infant's mouth.
Christian fundamentalist Julia Lovemore, 41, killed daughter Faith by stuffing her mouth with paper then dousing her in white spirit and jumping up and down on her body.
Two health workers had visited the home in Milton, near Cambridge, earlier the same day and found her husband David in the grips of a psychotic episode, but had failed to act.
The computer games designer, 39, had been frantically praying on the living room floor, shouting for the devil to be taken out of his wife.
The health workers even heard his wife call from downstairs, but left without seeing her to arrange a formal assessment of the family.
Tragically, an hour later, Mr Lovemore carried his lifeless baby into Milton Health surgery, along with their first child, who was critically ill after being doused in white spirit.
Lovemore admitted manslaughter on the grounds of diminished responsibility and was detained indefinitely under the Mental Health Act.
Other fatal errors by the Cambridgeshire and Peterborough NHS Trust included the shocking loss of records detailing an attempt by Lovemore in 2006 to smother her first child with a pillow to stop her crying.
There was also a three-month gap when the family were left to their own devices after a mismanaged handover between mental health teams, a serious case review revealed.
Furthermore, Lovemore had called a nurse five days before the death to say she wanted no further visits - a common sign of a relapse - which the report said should have alerted staff to the danger she posed.
Mr Lovemore had told social worker earlier that month that if Faith or her sister got into difficulty, he would pray first. 'He never said yes or no to calling a doctor,' prosecutor John Farmer told Cambridgeshire Crown Court in June 2010.
Lovemore's aunt had reported her to authorities after becoming concerned over her 'religious fervour', saying she had distanced herself from her family, branding them 'heathens'.
The report has now criticised Cambridge County Council, local police and the NHS trust for failing to protect the girl, who died in June 2009.
It said there was lack of 'assertiveness' in making Lovemore take her medication.
It was ruled that too much time was spent on determining whether the family's extreme religious views were a sign of mental illness rather than looking at the risk they posed to the children.
The report said: 'There was a failure to collectively recognise the extent to which this family were a risk to their children once they were mentally unwell.'
It added that the risk the mother posed to her children was 'not understood in the light of her past behaviour' because of the loss of any record of her attempt to hurt her other daughter.
The report concluded: 'We have no doubt that all the professionals working with Mr and Mrs A [the Lovemores] wanted to help them and were really concerned about the health of both parents.
'However, it is evident that significant systems and processes were not adequately in place and as a result Mrs A and her children were allowed to slip though the safety net of care.'
Dr Chess Denman, medical director at the Cambridgeshire and Peterborough NHS Foundation Trust, said the trust had now acted on the recommendation of the serious case review.
He said: 'We have already responded to the recommendations of the Serious Case Review and our own thorough internal investigation.
'We are now implementing a robust action plan in response to the external inquiry’s findings, including reviewing our risk assessment process and further increasing our focus on quality and safety.'