A mother who killed her six-year-old son had a history of violence and mental illness that was not picked up by police, council or health bodies, an inquiry has concluded.

The woman complained about hearing voices stating that the child was possessed by evil spirits, but her fears were not followed up.

Three months before the child’s death, the mother contacted Birmingham City Council’s Children’s Services to request help as she was struggling to cope.

Extended family support was put in place, but it proved too late to save the child, who was strangled in 2007.

The woman pleaded guilty to manslaughter on the grounds of diminished responsibility and was sentenced to a minimum of three years in prison.

Details of a subsequent investigation into the tragedy have been revealed for the first time by Birmingham City Council’s Safeguarding Children Board.

An inquiry highlighted the failure of police, council and the health trusts to work together and share information.

West Midlands Probation Service manager Simon Lomas, who chaired the inquiry, found that both the mother and the boy’s father had a history of violence.

He said: “There were 30 reported incidents of disputes with neighbours, with the police receiving domestic abuse referrals, the majority where the father was the victim.

“The police appeared to take little account of child safeguarding issues during these episodes.

“The mother’s violence was reported to agencies, but these were not progressed through an inter-agency approach.

The inquiry concluded that, although many agencies demonstrated a “high standard of service”, there were failings that have been acknowledged.

Mr Lomas said: “There were a number of milestones when agencies should have shared information about the mother’s recurring mental health and the potential risks to the safety and well-being of children.”

Four Serious Case Reviews, explaining the reaction of public agencies to cases of child abuse deaths, have been posted on the board’s website.

The move came mid-way through a 12-month improvement notice placed on Birmingham Children’s Services by the Government.

The council was ordered to do better after Ofsted inspectors found services for children at risk of physical and sexual abuse to be inadequate.

Ofsted told the council it was unhappy about the quality of the Serious Case Reviews and ordered the reviews to be reconducted.

The three other cases concerned:

n A baby who drowned in a bath at home after being left unattended by her young mother for 20 minutes.

The 22-year-old mother was a lone parent living in a high-rise flat with three children under the age of four.

The Serious Case Review concluded that families in similar circumstances should be targeted for support.

n A five-year-old child stabbed by its mentally-ill mother while she was having a psychotic episode.

The night before the incident the mother telephoned her support worker who recognised that she was not sounding well. But no help was given immediately.

n A child under 18 months who died after suffering severe internal abdominal and head injuries.

The mother was acquitted of gross negligence manslaughter, but her boyfriend was found guilty of murder and sentenced to life imprisonment.

The inquiry found that the probation service failed to keep tabs on the boyfriend, a convicted criminal.