In the small room above the Hillsborough Justice Campaign shop in Anfield, Kenny Derbyshire is used to meeting strangers. "Survivors still turn up out of the blue. They'll stand there, numb, unable to speak and break down in tears. This city is still suffering, until we get the truth no one can move on."

This week, 23 years after 96 football fans died at Hillsborough, the city of Liverpool hopes that, finally, the truth will out.

An independent panel of experts, chaired by the Bishop of Liverpool, James Jones, has spent 20 months examining 450,000 internal documents relating to Britain's worst sporting disaster.

On Wednesday, the panel will aim to deliver a definitive narrative into the events of 15 April 1989, when a fatal crush developed at the Leppings Lane end of the Sheffield stadium before an FA Cup semi-final between Liverpool and Nottingham Forest.

Sources say it will find "in favour" of the families and illustrate, in detail, the lengths to which South Yorkshire police orchestrated a "cover up" to hide their culpability by blaming the fans. The city hopes this will be the week that will finally clear the names of the supporters, who were maligned as drunk, ticketless and unruly, a portrayal perpetrated by police and articulated by the Sun newspaper under the headline: "The truth".

Michael Mansfield QC, who will be with families at Liverpool cathedral this Wednesday to offer free legal advice following the release of the documents, hopes myths will be laid to rest. The lawyer, who specialises in miscarriages of justice, said: "It was a false story, it's time to put it to bed."

Margaret Aspinall, whose son, James, 18, died, said the smear campaign directed by those culpable for the disaster had deepened Liverpool's grief. "It's not just the survivors, we have to clear their names [the dead] … I get angry when I think they have allowed the families to suffer for 23 years, to allow the survivors to go through torture knowing it was a cover-up."

No one from the government or police has apologised and no organisation or individual has been sanctioned, despite Lord Justice Taylor's official inquiry in 1989 which found that police failures caused the tragedy. "Liverpool has always been a militant town, but the attitude to Hillsborough destroyed any trust in the government. It can never be repaired," says Derbyshire.

He agrees that the sense of injustice has amplified the emotional fallout from a tragedy that keeps claiming victims. The Hillsborough Justice Campaign knows of least six survivors who have taken their own lives because they could not come to terms with the disaster or the official response it drew. Two weeks ago, a male survivor threw himself beneath a train.

"There a lot of walking wounded out there, broken marriages, people turning to drink," says Derbyshire, 46. "Thousands remain traumatised. To many it feels like it happened yesterday."

Aged 22, Derbyshire was yanked to safety from the crush by fellow supporters. "I can still hear the screams, people begging for help, people going down and not coming up again." He stares across the street to Liverpool's Kop stand. "I've survived because I've learnt to talk about it."

If the verdict, as expected, chronicles errors by the police and other public bodies, the demand for fresh inquests will be overwhelming. For the Hillsborough families, the coroner's hearings into the 96 fatalities, and subsequent verdict of accidental death, cannot be allowed to stand. In particular, Dr Stefan Popper's decision to impose an "artificial" cut-off at 3.15pm on the day of the tragedy, after which point no evidence was taken, has been condemned. It has always seemed a curious decision to many, coming just 11 minutes after a barrier snapped on the terracing of the Leppings Lane end, causing the 3.04pm "surge" which prompted the worst of the crushing.

For the first time, details of what happened after 3.15pm on the day of the crush, in which 766 were also injured, will emerge this week. In particular, the documents are expected to dissect the chaotic response by the emergency services. Just one out of 42 ambulances summoned to Hillsborough made it on to the pitch. Only 14 of the dead were taken to hospital. Paramedics have said the basic practice of clearing patients' airways was not done.

Crucially, a clearer picture of how many more lives might have been saved is expected to emerge. It is apparent that some were alive long after 3.15pm. "Different places, different times, different reasons, but obviously some were alive beyond that point," said Mansfield.

Reports have described bodies laid by the river Don, presumed dead. Corpses were left by the Leppings Lane end, though no qualified medic had examined them. How many of the dead could have been saved? One mother, Anne Williams, whose son Kevin, 15, died, has evidence that her son displayed signs of life at 4pm. An off-duty officer told her he felt a pulse. A special constable said Kevin opened his eyes and whispered: "Mum". Their statements were changed following a visit from West Midlands police, whose serious crime unit was disbanded in 1989 amid allegations of corrupt conduct by officers. Both witnesses stand by their original statements.

Signs are growing that the government could lodge an application to the high court for a round of fresh inquests. The attorney general, Dominic Grieve, promised yesterday to consider this week's evidence and then decide "as quickly as I can".

Aspinall, vice-chair of the Hillsborough Family Support Group, admits she is haunted by the thought that her son might have survived. "I don't know what happened or who helped my son. Why was he laid on his back and not in the recovery position? Who said he died at ten to four?"

Clues to the extent of the alleged cover-up can already be found in documents from South Yorkshire police released several years ago, after a government order. They show how a unit of senior officers vetted junior officers' statements. Criticisms of the police were ordered to be removed, yet the undoctored statements betray a police leadership in disarray. More darkly, they indicate a smear campaign against Liverpool supporters. One fan, said to have vomited beer, was found to have no alcohol in his system. In one statement, an officer bizarrely wrote: "Liverpool fans murdered Liverpool fans."

South Yorkshire police have still to explain by whom and why the notebooks were doctored. Not one officer among the 800 on duty that day has said sorry. Although Derbyshire reveals that a couple have rung his campaign group anonymously, the lack of a public apology rankles.

Aspinall said: "Not one has had the balls to come out and say we were told to change our statements, not one." The ongoing silence compounds the feeling that the force remains reluctant to accept responsibility.

It is hoped that on Wednesday the panel will give reassurances that they have received all the documentation relating to Hillsborough. The fact that, 14 years after Lord Justice Stuart-Smith's judicial scrutiny of Hillsborough evidence, hundreds of thousands of documents are about to be disclosed corroborates the suspicion of a system operating against the families' interests.

Aspinall added: "If anything new comes out on Wednesday, then it means not one person has wanted to release it to us despite all our attempts. Why was that?"