Social workers who missed crucial opportunities to potentially save a mother murdered by her boyfriend have never been disciplined and may still be working in the profession.

Nanny Charito Cruz, 37, was hammered to death by boyfriend Asad Niazi in front of their two-year-old daughter at their home in Cambridge Road, Kingston, in 2011.

A review of the case last year revealed a series of failings by various agencies, including social workers not logging records of referrals from the NSPCC until the day after Miss Cruz died.

A team leader also decided Niazi showing his daughter a pornographic video was “not significant”.

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Now the Health and Care Professions Council, which regulates social worker standards, has confirmed that no action was ever taken against anyone involved in the case.

It could not confirm if any hearing was pending.

A former Kingston social worker, who did not want to be named, said: “The fact that none of these team leaders faced any internal or independent investigation of their actions leaves me in great doubt about whether they have addressed or improved their safeguarding practice.

“Without an investigation I would have no confidence in using any of them in a responsible safeguarding role – at any council.”

She added the actions of one particular social worker, known as TL3, “would have resulted in various interventions that same day, any of which could have changed the family’s circumstances”.

Previously whistleblower Olivia Butler, former head of social care at Kingston Council, claimed computer records within social services had been altered to “cover up the lack of action and proper response” by social workers dealing with the case.

But her claims were refuted by then-council leader Derek Osbourne and chief executive Bruce McDonald.

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The domestic homicide review, published in November, also failed to uncover the truth, saying it had not been possible “to firmly conclude which version of events is truthful”.

But the report’s author, Davina James-Hanman, said she believed at least one out of three former Kingston Council social workers had been investigated for their alleged offences.

Asked whether the workers should have been investigated or disciplined, Ms James-Hanman said: “That did not fall within my remit of a domestic homicide review.

“My remit was what would have made a difference.”

Kingston Council has previously confirmed that everyone involved in Miss Cruz’s case no longer works for the authority.

It is unknown whether any were sacked or disciplined before they left.

It is believed at least one former Kingston Council worker involved in the case is still a registered social worker.

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The scene of the crime: Cambridge Road, Kingston in September 2011

John Cameron, head of child protection operations at the NSPCC, said: “Concerns for the welfare of adults, who are possibly victims of domestic violence, should not be overlooked by children’s services, even if there are no allegations of harm to children.

“Agencies should consider the possible harm to all members of the family not just children when concerns are raised.

“It’s vital that agencies who take responsibility for assessing incidents report back the action they have taken to those agencies who have referred to them those concerns.”

Nick Whitfield, Kingston’s director of children’s services, declined to comment.

A spokesman for AfC, Kingston and Richmond’s joint children’s services company, said: “We cannot comment on matters that are strictly confidential.”