The crucial minutes between gun maniac Raoul Moat phoning 999 to say he was hunting for police and him shooting Pc David Rathband in the face will be the subject of a High Court action.
The officer's twin brother Darren and sister Debbie Essery are taking Northumbria Police to court, claiming the force was negligent in not passing on the warning to staff on patrol that night.
Had he known about the specific threat, they say, he would not have been sat stationary in his patrol car on a prominent junction above the A1 in Newcastle, and could have kept mobile.
Moat killed himself on the banks of Rothbury’s Riverside in the early hours of July 10, 2010, after a six-hour stand-off with police following a huge manhunt in Northumberland.
In the minutes after Pc Rathband was blasted twice by the ex-doorman, senior officers ordered all unarmed police to return to their stations, the Rathbands' legal team have stated in their claim which is to be heard in the New Year.
In the early hours of July 3 2010, Moat shot his ex-partner Samantha Stobbart and murdered her new lover Chris Brown in Birtley, Gateshead, and went on the run.
Before going on patrol, Pc Rathband read through a log of "60 pages of random information" collated by Northumbria Police on the manhunt. He received no express instructions about the ongoing search, his family will claim.
That next night, Moat spoke to a Northumbria Police call handler for almost five minutes, saying he would kill any officer who came near him, that he was not coming in alive and, at one point, that he was hunting for officers.
He ended the call at 00.34 on July 4, the claim states, and Pc Rathband was shot at around 00.42.
Approximately two minutes before, his claim says, one Northumbria Police employee phoned a supervisor to ask if "something was going out over the air regarding the threats".
The Rathband claim said no action was taken.
The father-of-two was blinded after being shot twice, as well as being left with considerable and painful injuries to the face and shoulder. He lost his sense of smell and taste, felt sick every day and lost three stones.
His pain increased through the day and kept him awake at night. He killed himself in February 2012 aged 44 at his home in Blyth, Northumberland, and the case is being brought on his behalf by his siblings who are executors of his estate.
The claim states Pc Rathband was on his usual duties that night, but was also part of the search for Moat and had parked on a busy roundabout which the gunman or other offenders might use.
His legal team said: "Had the Deceased been given any warning that Moat was out hunting for police officers, he would have immediately moved from his highly visible stationary position and would have followed such instructions as were given, but in any event would have kept his vehicle in motion."
The claim said Northumbria Police conducted an internal review the following month and concluded it was not possible to draw up and communicate a "fully risk-assessed" response to the threat in those critical minutes between the 999 call and Pc Rathband being shot, but some "interim" warning could have been made.
One suggestion was that officers on patrol could have been told not to remain static, but to keep mobile until further direction.
The Rathbands claim that the force had a duty of care to the officer to pass on a warning and was negligent.
The legal case was started by Pc Rathband himself, and originally any damages if he won would have had to cover his on-going care.
It will be heard at Newcastle Crown Court on January 12 and will last two weeks.
Northumbria Police declined to comment.