A misconduct hearing against five police officers following the death of a man in custody has collapsed.
Leon Briggs, 39, died in hospital on 4 November 2013 after being restrained and detained at Luton police station.
The Crown Prosecution Service said in 2018 that no officers would be charged over the death but a misconduct hearing was due to begin on 3 February.
Mr Briggs' family said they were "devastated and outraged" at the decision not to continue proceedings.
His mother Margaret Briggs said: "It is over six years since my son's death and to be told that the officers will not face any public scrutiny is further denial of justice and accountability for Leon."
Mr Briggs, from Luton, was being held under section 136 of the Mental Health Act following concerns about his behaviour on Marsh Road in the town.
Section 136 gives police the power to take a person of concern from a public place to a place of safety.
Mr Briggs was restrained and placed in a cell at the station. He became unconscious and was pronounced dead in hospital.
Bedfordshire Police Federation chairman Jim Mallen said the misconduct hearing collapsed due to "numerous failings" by the Independent Office for Police Conduct (IOPC) which "meant the officers could not be guaranteed a fair hearing".
A spokesman for the IOPC said the the misconduct proceedings ended due to "the decision of Bedfordshire Police to offer no evidence".
"Leon Briggs' family have waited many years for the actions of the police officers involved to be scrutinised in public," he said.
"The last minute actions of Bedfordshire Police and the most recent delays mean that his family have been denied that right."
Mrs Briggs said it was important to have answers about what happened that day "to make sure others don't die in similar circumstances".
"We cannot understand why the issues raised at this stage were not dealt with earlier," she added.
"We have lost all faith in the IOPC and systems that are meant to ensure officers wrongdoings will not go unchecked.
"The decision sends a wider message that officers can act with impunity, a message that should be a cause for concern for everyone."
Mr Mallen said the collapse of misconduct proceedings meant the officers involved could "finally get on with their careers and lives".
"A cloud has unfairly been hanging over them since 2013. This has changed their lives, their family's lives and their careers immeasurably," he said.
He said more than £1m of public money had been spent on the officers' pay while they had been suspended.
Bedfordshire Police Assistant Chief Constable Jackie Sebire said: "The force has always wanted a fair and transparent hearing to provide answers to the family of Mr Briggs and provide confidence to the public.
"However, we became aware during the initial legal arguments of failings in the independent investigation which called into question the proportionality, fairness and the public interest in continuing with this hearing."
She described the decision as a "regrettable and unfortunate situation which could, and should, have been resolved a long time ago".