The family of Pc David Rathband has said the officer - who was blinded after being shot by Raoul Moat - was "let down by the people that could have prevented his death".
The comments were made as they attended the inquest into Pc Rathband's death, two years after he was found dead at his home.
The 43-year-old was left blind and fighting for his life after Moat shot him twice while he was on the run in July 2010.
Speaking outside Moot Hall, Newcastle, Mr Rathband's father Keith said: "The evidence that the coroner has been given identifies that David was let down by the people that could have prevented his death.
"The findings of the coroner may be a foregone conclusion to many. Our hope is he finds David's death was preventable in the circumstances."
Mr Rathband's sisters, Debbie Essery added: "Northumbria Police investigated a complaint made by David's brother Darren. Into those issues the investigation found there was no case to be answered. As a family, we do not accept this.
The findings of that investigation are contradictory to the evidence the coroner has been given."
Pc Rathband won national praise for his battle against disability and for setting up a charity to help other emergency workers injured in the line of their work. He was found hanged at his home in Blyth, Northumberland, on February 29 2012.
David Rathband had an affair with 7/7 survivor Lisa French in the months before he died which effectively ended their marriage, his widow told an inquest into his death.
Mrs Rathband told the inquest the officer could not understand why she would not take him back and rang her up to 100 times a day.
She visited him at his home on the evening he hanged himself and was concerned enough to call his welfare officer, Inspector John Heckles, and to text his sister in Staffordshire.
But, despite her fears, she did not consider he was going to kill himself, Kath Rathband told the hearing.
An inquest into the death of Chris Brown, who was murdered by gunman Raoul Moat, heard the late killer was unbalanced and would get angry when talking about his former partner Samantha Stobbart and the police.
A witness, who was a prisoner alongside Moat at HMP Durham, told the court: "He indicated that he was going to take some sort of revenge against her and her partner."
The court heard that Moat had made it clear that he would never return to prison whatever happened and that he had also boasted about having access to a shotgun and explosives.
Mr Brown, a 29-year-old karate Instructor, had recently begun a relationship with Ms Stobbart when he was shot dead by Moat in July 2010.
A coroner's inquest has begun into the death of Chris Brown, who was murdered by Raoul Moat during the gunman's rampage in Newcastle three years ago.
Brown's family's say the focus has always been on Moat himself, rather than his victims, and until now their requests for an inquest have been denied.
Sally Brown, the mother of Chris Brown who was shot by Raoul Moat, described losing her son as hell.
"Christopher's death has been horrendous for the whole family. Only one word can describe how horrible, it's been hell."
An inquest into the death of Chris Brown, who was murdered by Raoul Moat in 2010, has heard evidence from a prisoner who served with Moat at Durham Jail.
Prisoner known only as 'N1' says he spoke to a prison officer shortly after moat was released. He says he made an off the cuff remark
'He is going to end up killing somebody'
N1 also says Moat had spoken during his time in jail of 'exacting some sort of revenge'
Survival expert Ray Mears has revealed his role in tracking Raoul Moat through woodland more than three years after the gunman went on the run in Northumbria.
Speaking to the Gloucestershire Echo, Mears described the scene as like something "out of a Hollywood film set” and said he has not spoken of his role until now for fear it would be seen as a, "publicity stunt."
Moat had been on the run for a week after shooting his former partner, Samantha Stobbart, killing her new boyfriend, Chris Brown, and blinding PC David Rathband, when a search adviser working on the case got in touch with the TV presenter and wilderness expert for his tracking skills.
Mears added: “I have experience of tracking for 40 years. I can’t imagine there would be that many people in the country who would have been in a position to help the police find someone who had gone into hiding who needed to be found.
“It was a real-life hunt; within my skill set but outside of my comfort zone.”
Northumbria Police has said: “We can confirm Ray Mears did assist in this investigation, as did several other agencies and specialists."
The Independent Police Complaints Commission (IPCC) investigated officers' involvement with Moat and, in its report last year, said that "
intelligence came to light that whilst in prison he had allegedly made threats to cause serious harm to his girlfriend.
The intelligence was forwarded to Northumbria Police during the afternoon of 2 July and this is subject of a separate IPCC Investigation Report."
According to the BBC the information was passed between various prison in-trays and was read and signed by at least three senior officers. It was then passed to Northumbria Police but the IPCC said there was 'confusion' over the identity of Moat's partner.
The report said there was no evidence of misconduct.
Hundreds gather for the funeral of PC David Rathband, who committed suicide last month after being blinded by gunman Raoul Moat in 2010.Read the full story ›
"I have always known that David was struggling to cope with his blindness, that he was left with on that horrible day, the fourth of July.
How ironic that American Independence Day was the day he lost his independence and I lost some of me.
Sadly we are a broken family from his passing and there is grief in all of us. I hope that those who carry a burden after his death carry it with themselves and don't aim to lay that at his graveside. It is just as cowardly to judge an absent person as it is wicked to strike a defenceless one."