A public inquiry into the Nottingham attacks revealed a "catastrophic collapse of responsibility" and an "undoubted miscarriage of justice", the mother of one of the victims has said.
Valdo Calocane, who had been diagnosed with paranoid schizophrenia in 2020, stabbed to death Barnaby Webber, Grace O'Malley-Kumar and Ian Coates, and tried to kill three others in Nottingham on 13 June 2023.
The lead-up to the attacks and the aftermath were scrutinised during a 14-week public inquiry, which concluded on Friday.
Speaking at a press conference in London on Monday, Barnaby's mother Emma Webber said: "It has been brutal, bruising and harrowing beyond measure - but it was so very necessary. "
Emma added there had been "cover-up over candour".
She said: "This wasn't bad luck. It was a catastrophic collapse of responsibility. An undoubted miscarriage of justice that must now be addressed."
The Nottingham Inquiry - the hearings of which began on 23 February and ended last week - laid bare a series of failings by authorities, including the NHS and police, in the years leading up to the attacks and in the aftermath.
Calocane is currently serving an indefinite hospital order after pleading guilty to three counts of manslaughter on the grounds of diminished responsibility, and to three counts of attempted murder.
The bereaved families have maintained the attacks were avoidable and never been happy with Calocane's sentence.
Emma said while the families awaited the findings of the inquiry, it did not prevent action from being taken now.
"Excuses stop here and accountability starts today," she added.
Now oral evidence has concluded, the core participants of the inquiry will share closing statements at hearings in September, before the chair of the inquiry - retired senior judge Deborah Taylor KC - is expected to release a report with her recommendations next year.
Ian's son, James Coates, said for "what felt like a very long time", he and the other bereaved families, believed "institutions did everything they could".
"Unfortunately, we were delusional in our belief that justice would be served," he added.
"For two and a half years, we've watched organisations close ranks, mark their own homework, and the inquiry must be the true reckoning."
The public inquiry heard how staff at a number of organisations, including Nottinghamshire Police, inappropriately viewed records or information related to the fatal attacks.
In May, Nottingham University Hospitals NHS Trust confirmed it had dismissed 11 members of staff for inappropriately accessing medical records, while 12 had received final written warnings and two had first written warnings.
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