A friend discovered Madeline and Lauren O'Neill's bodies
A mother who killed her daughter and then committed suicide had told health professionals about her intentions, a report has found.
Madeline O'Neill took her own life after killing her daughter, Lauren, at their home in Carryduff in July 2005.
The report criticised the care Mrs O'Neill received from the Eastern and Western Health Boards and said they had failed to follow basic procedures.
Mrs O'Neill left Gransha Hospital in Londonderry two weeks before her death.
According to the investigation, Mrs O'Neill told her GP, a private counsellor and a psychiatrist at Knockbracken Mental Health Hospital in Belfast about her plan to kill her daughter and take her own life in the weeks preceding her death.
However, despite this no-one told her estranged husband or gave him the opportunity to protect his daughter.
"Communication from Knockbracken to Madeline O'Neill's GP and her father was poor," it said.
"(There is) little evidence of systematic communication with the patient's family either in Knockbracken or Gransha."
Mrs O'Neill's estranged husband John said he would be "haunted forever" that Lauren's death was easily preventable.
Mr O'Neill said he believed "those who bear responsibility for these untimely deaths should be held fully accountable for their shameful neglect of care".
Mrs O'Neill was originally from Londonderry, and received her last hospital care in the city's Gransha Hospital.
She had also been a patient at Knockbracken Health Care Park in south Belfast.
Health Minister Michael McGimpsey said every one of the 36 recommendations in the report would be acted on.
He said he would set up a public inquiry if necessary.
"We have to take the steps to ensure that such a situation that occurred with Madeline and Lauren won't happen again," he said.
Both boards said they received the department's report last May and are implementing its findings.