The boyfriend of a pregnant woman murdered with her son by her mentally ill former partner has called for better communication between the authorities to prevent such tragedies from happening again.
He was speaking after a serious case review found that the deaths of Rachael Slack, 38, and 23-month-old Auden could not have been "reasonably predicted".
The pair were killed by Ms Slack's former partner and Auden's father, 44-year-old Andrew Cairns, who had a history of mental illness. He was also found dead at the house in Holbrook, Derbyshire, slumped over her body, after turning the knife on himself.
A jury at an inquest last year was critical of police for failing to impress upon Ms Slack that she was at high risk of homicide after she had contact with officers about Cairns's increasingly worrying behaviour.
Ms Slack's boyfriend Robert Barlow said the report highlighted that more needs to be done and suggested a "uniform document" be introduced so police and mental health services can share information.
"Things have got to change - policies, structures have got to change," Mr Barlow told ITV's Daybreak.
"Everybody has got to learn to communicate and share the information through the professional bodies. There's too much fracture between the police and mental health and the carers. Basically the left hand doesn't know what the right hand is doing.
"The information was there, it's just that the professionals didn't have all the information at any one given time for them to act accordingly and make a life-changing decision."
Mr Barlow said the deaths in June 2010 had made a "massive hole in the family's life" but added he was trying to focus on making changes rather than his own sorrow.
"I have to think past myself, it's about making changes, there's no point me barking on about how sad it is, how it's changed my life, everybody's life. It goes without saying that it's left a massive hole in the family's life," he said.
"We need changes, that's what I've got to focus on. It would help me focus my disappointment, my sheer disappointment, knowing that something is going to change - the future Rachael and Audens are going to be better looked after."
Following the inquest, Mr Barlow said " she could have been alive today" if the severity of Cairns's threats had been understood.
The serious case review by Derby Safeguarding Children Board (DSCB) found that the tragedy could not have been foreseen with information known at the time.
In the months leading up to the deaths, Cairns - who had a history of mental illness dating back to a 1999 suicide attempt - had become increasingly depressed and his behaviour more concerning for family and Ms Slack, who continued to check on him even after their relationship broke down in late 2008.
The DSCB report considered a number of factors, including threats made by Cairns to kill Ms Slack on May 27, 2010, after she told him she was in a new relationship and expecting a baby.
Cairns, a former golf tutor, made the threats hours after being detained by police under the Mental Health Act when Ms Slack had driven him to the police station because he refused to get out of her car and she was worried about his behaviour.
He was assessed by mental health workers and released after he was found to have no major mental illness.
On May 27 he was again arrested after making the threats to kill Ms Slack but released on police bail the next day after denying the accusations.
The report said Derbyshire Constabulary receives 150 to 160 reports of threats to kill each year and their analysis identified this case as the "only one of those reports over at least a three-year period which has been followed by enactment of the threat".
Officers had no contact with Ms Slack or Cairns about his mental health issues which "would have effectively discriminated this case from any of the other 'Threats to Kill' reports".
The police were also not made aware of Cairns's behaviour after his release from custody, or that he had been hanging around outside Ms Slack's house after his release.
In addition, the report found mental health professionals did not know about the events of May 27 or those afterwards.
"Only an extremely small number of individuals who share the characteristics of depressive mental illness and involvement with mental health professionals go on to commit such acts," the report said.
It concluded: "On this basis the review has concluded that no individual or agency could have reasonably predicted that (Cairns) would kill (Auden) and (Ms Slack), thereafter taking his own life, as is believed to have occurred on the morning of 2 June 2010."
Although the killings were not predictable, the report said, the risk assessment carried out after Ms Slack contacted police indicated that Cairns posed a serious risk to her and although she was advised by officers not to have any contact with him she was not convinced of the risk.