The families of the three victims killed by Valdo Calocane in Nottingham have spoken out after a judge ordered he be detained at a high-security hospital "very probably" for the rest of his life.
The mother of 19-year-old Barnaby Webber told Nottinghamshire Police "you have blood on your hands", as she spoke outside the court on Thursday.
In a series of missed opportunities to prevent the killings last year, Calocane had previously been detained in hospital four times, and a warrant for his arrest had been issued months before his deadly rampage.
Emma Webber said: "True justice has not been served today. We as a devastated family have been let down by multiple agency failings and ineffectiveness."
After the verdict, Nottinghamshire Police assistant chief constable Rob Griffin said there was not anything "obvious" to suggest the killer would launch the attacks.
Mr Griffin cited "relatively low level assaults" by Calocane in the past which did not indicate he would commit the attacks on 13 June.
'Mockery of the system'
James Coates, son of victim Ian Coates, said the killer had "got away with murder".
He added Calocane had "made a mockery of the system" and if he had not been stopped when he was it "could have been one of the most catastrophic attacks this country has ever seen".
He blamed the police, the Crown Prosecution Service (CPS) and the health service for his father's death, saying they all failed.
"All we can hope is that in due course some sort of justice will be served," he said.
Father of 19-year-old Grace O'Malley-Kumar, Dr Sanjoy Kumar, described the last few days as "absolute hell".
He said the family will "never come to terms" with her loss and how she died saying Grace was a "gift to us, she was a gift to the country".
Dr Kumar said the family never questioned Calocane's diagnosis of paranoid schizophrenia, but pointed to a "lack of toxicology [reports]" and "contemporaneous mental health assessments" during the case.
He said there were "missed opportunities" to "divert [Calocane's] lethal calls" that will "forever play on our minds".
Prosecutors accepted 32-year-old Calocane's guilty pleas to manslaughter, not murder, on the basis of diminished responsibility. He also admitted three counts of attempted murder after hitting three pedestrians in a van he stole from Mr Coates.
Calocane repeatedly stabbed the teenagers with a dagger as they walked home after a night out to celebrate the end of their exams.
He also knifed school caretaker Mr Coates, 65, to death as he made his way to work at Huntingdon Academy in the early hours.
'Foolishly' trusted in the system
On the CPS, Ms Webber said the agency "did not consult us as has been reported - instead we have been rushed, hastened and railroaded".
"We were presented with a fait accompli that the decision had been made to accept manslaughter charges," she said.
"At no point during the previous five-and-a-half-months were we given any indication that this could conclude in anything other than murder.
"We trusted in our system, foolishly as it turns out.
"We do not dispute that the murderer is mentally unwell and has been for a number of years.
"However the pre-mediated planning, the collection of lethal weapons, hiding in the shadows and brutality of the attacks are that of an individual who knew exactly what he was doing.
"He knew entirely that it was wrong but he did it anyway."
CPS explains manslaughter decision
The chief crown prosecutor for the East Midlands, Janine McKinney, said Calocane was assessed by three expert psychiatrists, all of whom said his actions were influenced by paranoid schizophrenia.
The condition had a "significant impact" on his actions and "impaired his ability to exercise self-control", she said.
It gave him a legal right to put forward a partial defence to murder and offer manslaughter pleas, Ms McKinney added.
On reviewing the evidence, the CPS concluded "there was no longer a realistic prospect of conviction for murder, but there was for manslaughter and attempted murder", Ms McKinney explained.
"That is why we accepted the pleas."