A nurse accused of murdering patients was unlikely to have deliberately set out to harm them, an inquiry has found.
Anne Grigg-Booth, from Nelson, Lancashire, was accused of killing three women aged 96, 75 and 67 at Airedale Hospital in West Yorkshire.
The ex-matron, who was accused of injecting patients with high doses of painkilling drugs, died in 2005.
The report found a catalogue of systemic failures in the way she was allowed to carry out her work.
Bridget Fletcher, chief nurse at Airedale NHS Trust, said it had made "significant improvements", particularly since 2005.
"We would like to reassure both patients and the local community that patient safety is, and always will be, our highest priority."
A joint statement by West Yorkshire Police and the Crown Prosecution Service (CPS) said it was satisfied the police inquiry was "thorough" and that the decision to prosecute Ms Grigg-Booth had been "the correct one".
The report also found Ms Grigg-Booth - described in the report as "hard working, caring and experienced" - had used clinical records, charts and notes to record her actions.
It said these records were "entirely open".
The report concluded the events investigated "occurred as a result of a combination of individual and systems failure".
Ms Grigg-Booth, who had worked at the hospital for 25 years, died aged 52 before she could stand trial at Bradford Crown Court.
The charges related to her injecting patients with high doses of painkilling drugs such as morphine and diamorphine on the night shift.
The nurse, who was often in charge of the night shift during her work at Airedale NHS Trust, was not supervised properly, the independent inquiry said.
After her death, detectives from West Yorkshire Police said they believed she could have killed many more patients.
The report found she was "utterly convinced of her own clinical prowess" and at night "she was effectively in charge of the hospital".
"The most striking failure was in the disconnection between what was happening on the wards at night, and what the [trust] board knew," the report added.
'No Beverley Allitt'
The CPS decided there was only enough evidence in three of the deaths to press murder charges.
Eddie Kinsella, an independent inquiry team report member, said Ms Grigg-Booth should not be "demonized" following the report's publication.
"She and other senior night nurse practitioners reasonably believed they were acting with the authority of the board as a whole. The board did not understand that," he said.
Ms Grigg-Booth was charged in September 2004 and was due to go on trial in April 2006, but she was found dead at her home after she took an accidental overdose of anti-depressants in August 2005.
The nurse was accused of murdering June Driver, 67, in July 2000, who was being treated for an infection after a hip replacement; Eva Blackburn, 75, in November 2001 and 96-year-old Annie Midgley in July 2002, after she was admitted with abdominal pain.
She was also facing 13 counts of unlawfully administering poison to 12 other patients and another of attempting to murder 42-year-old Michael Parker in June 2002.
Ms Grigg-Booth had denied the offences.
The report also said the nurse was "not a Beverley Allitt".
Allitt is serving 13 life sentences for attacking and murdering children in the Lincolnshire hospital where she was a nurse.