Police say any one of a series of errors by them and hospital authorities on the day a woman was killed by her mentally ill former neighbour could have been responsible for her death.
They have admitted that the death of Diane White in Hamilton in January 2010 could have been prevented. Her inquest ended in Hamilton on Friday.
The 53-year-old was killed after being hit by Christine Morris using a hammer during a frenzied attack at her Hamilton home.
Two years later, Morris was convicted of the murder and sentenced to life, with a minimum non-parole period of 10 years. She is a paranoid schizophrenic with a borderline personality disorder.
Police carried out a review after the killing and a number of procedural faults were identified, the inquest was told.
Detective Inspector Chris Page said the mistakes started from when Waikato Hospital was trying to get through to police to report Morris' escape from its mental health unit.
Also, Morris was not chased by hospital staff and her support worker saw her walking down the road and didn't stop her.
Police failed to send a patrol to Mrs White's address immediately before the killing and that dispatchers merged emergency calls into one, not realising the severity of the situation.
The review has also identified a lack of reference in the police manual on how to deal with mental health patients and that a number of patients had escaped from the unit before, including Christine Morris.
Police said recommendations have been made and actioned, including better training for officers to deal with mental patients and improvements in staff training in the communications centre.
Inspector Page said if one event had occurred differently, then the outcome would have been different, and told Mrs White's family that police had let them down.