The partner of a woman murdered with her young son insists that the deaths could have been prevented if information had been shared amongst agencies.

Andrew Cairns stabbed his pregnant ex-partner Rachael Slack and their 23-month-old son Auden in 2010 at their Derbyshire home before killing himself.

A Serious Case Review found that authorities could not have predicted that he would kill them but Ms Slack’s partner Robert Barlow and charity Refuge attacked the report, saying more could have been done.

Sandra Horley, chief executive of the national domestic violence charity, said the findings of the review “contradicted” the outcome of last year’s inquest, which found police failure to impress on Ms Slack the danger she and Auden faced “more than minimally contributed” to their deaths.

“The coroner at the inquest found that, despite making an assessment that Rachael and Auden were both at high risk of homicide, Derbyshire Police failed to discuss with Rachael adequate steps that could have been taken to address the risks to Auden,” Ms Horley said.

“The police also failed to inform Rachael that they had assessed her and Auden as being at high risk of homicide. As a result, Rachael was denied the opportunity to make an informed choice about her and Auden’s safety.”

Ms Slack’s partner at the time, Mr Barlow, said if information about Mr Cairns had been better shared between professionals, the deaths could have been prevented.

He said: “There were too many mistakes made throughout Andrew’s care and too many mistakes made with Rachael’s safety back at home after he was arrested.

Agencies and individuals didn’t have, or didn’t share information – it meant they couldn’t make whole judgements on decisions,” he said.

Their safety relied on those decisions being made properly.”

On 27 May he was arrested after making threats to kill Ms Slack but released on police bail after denying the accusations.

The report by the Derby Safeguarding Children Board (DSCB) said officers had no contact with Ms Slack or Mr Cairns about his mental health issues. They were also not told of his behaviour after his release from custody or that he had been hanging around outside Ms Slack’s home after his release.

“Other agencies and professionals had, at most, partial information regarding these events,” the report said.

The DSCB has made a number of recommendations, which include better sharing of information and monitoring of informal carers who provide support to people with mental health problems, particularly where children are involved.

ECINS Founder Gary Pettengell said “this case sadly echoes ACC Mark Hopkins of Cambs Police’s words at the ECINS Conference in November when he said “the consistent message around any review or any perceived failing is frequently that somebody, somewhere knew something and didn’t share it. Or that the association with one piece of information in one context wasn’t clear and a failing occurred.  The whole ECINS process is about engaging partners and making sure that we don’t lose those opportunities”.