Thousands of original Hillsborough witnesses to be re-interviewed
Thousands of witnesses to the Hillsborough disaster are to be re-interviewed as part of the fresh investigation by the police watchdog.
The Independent Police Complaints Commission (IPCC) wants people who were at the stadium in 1989 to contact its team examining the police actions.
The IPCC said its investigation was the biggest undertaken into police conduct in England and Wales.
Ninety-six Liverpool fans died after a crush at the FA Cup semi-final.
The match against Nottingham Forest was held at Sheffield Wednesday's Hillsborough stadium on 15 April 1989. Ninety-five fans died on the day and another died of his injuries four years later.
The IPCC's investigation, based in a mothballed building in Warrington, follows the damning report by the Hillsborough Independent Panel published last September.
The report concluded the lives of 41 fans could have been saved and cleared supporters of any wrongdoing or blame for the disaster.
It found South Yorkshire Police had altered more than 200 statements and tried to blame fans.
In the aftermath of the tragedy West Midlands Police was appointed to gather evidence on the original investigation for subsequent inquiries and inquests.
The IPCC has now revealed there were "differences" between fans' statements and questionnaires they returned to the West Midlands Police inquiry.
The police watchdog said it wished to speak to thousands of members of the public who gave those witness accounts either in writing, via telephone or interviews.
Deborah Glass, deputy chair of the IPCC, said the Hillsborough panel's report, had already raised "serious questions" about the work of the West Midlands force.
In the immediate aftermath of the tragedy, Lord Taylor began a judicial review assisted by West Midlands. The original inquiry into South Yorkshire Police formed the basis of the original inquests and brought no criminal charges.
The Hillsborough panel concluded last year that the South Yorkshire force had orchestrated a cover-up, falsified documents and blamed innocent supporters for the tragedy.
A separate investigation, led by retired chief constable Jon Stoddart, is looking at whether there are grounds for gross negligence manslaughter prosecutions with a number of public bodies connected with the tragedy.
His inquiry will provide evidence for the new inquest, set to start by 31 March 2014.
Ms Glass said: "We are now looking at how West Midlands Police conducted the investigation which supported the Taylor Inquiry and the original inquests.
"We know thousands of people gave eyewitness accounts to that investigation. We want to speak to those people about their experiences of dealing with West Midlands Police. We also know some of you may have never been able to give your account. This is your opportunity."
The IPCC wants to build the most comprehensive account there has ever been of what happened at Hillsborough from the people who were there on the day.
Ms Glass added: "There are still many questions to be answered for the families of the 96 fans who died; for the survivors who still live with the trauma of this unimaginable experience; for the people who lived under this terrible cloud for 24 years.
"The families, survivors and campaigners have fought tirelessly for the chance to allow your voices to be heard. Now that time has come."
Chris Mahaffey, a senior investigator, said: "When you make comparison with these questionnaires against other documentation that appears to come from the same person, there are differences. Who was actually directing this, if there was someone directing this?"