The biggest ever inquiry into police actions in the UK is to be launched following allegations of misconduct by South Yorkshire police, West Midlands police and others in the aftermath of the Hillsborough independent panel's report last month.
The Independent Police Complaints Commission said a large number of current and former officers will be investigated over the tragedy over 23 years ago, and during the alleged cover-up afterwards.
Margaret Aspinall, who lost her son in the disaster, reacts after the release of previously unpublished papers relating to the Hillsborough disaster.
Director of Public Prosecutions Keir Starmer also said he will look at whether any individual or corporate body should be charged over the football stadium disaster, which left 96 people dead.
The role of West Midlands Police will also be investigated along with those who led the initial investigation.
Margaret Aspinall, chair of the Hillsborough Family Support Group, welcomed the inquiry.
Speaking in Anfield, Liverpool, she said: "I can only repeat again what we said four weeks ago ... the truth is out there. I think the time is now for accountability.
The IPCC's deputy chair Deborah Glass said in a statement:
The [Hillsborough] report revealed extremely serious and troubling issues for the police. Its contents provoked a demand for those responsible for the actions revealed in the report to be held to account.
We have learned details of the run-up to the disaster including the unheeded warnings from previous incidents, the disaster itself, and its aftermath, including what appear to be attempts to distort the truth.
Since the report was published, the IPCC has been undertaking a thorough review of it and has also begun to examine the 450,000 pages of supporting evidence to identify what conduct, by named or unnamed police officers, requires investigation.
While the review was ongoing we received referrals from West Yorkshire Police Authority in relation to Sir Norman Bettison, South Yorkshire Police in relation to the events before, during and after 15 April 1989, and West Midlands Police in relation to their role in the investigation of events.
We have considered all of this and determined there are a number of matters which require investigation by the IPCC.
Bettison's reference comes over accusations he provided misleading information after the tragedy.
The families of Hillsborough victims have raised concerns over why Bettison has stepped down and whether he will receive his pension
He is also under investigation for allegations he "attempted to influence the decision-making process of the West Yorkshire Police Authority in connection with the referral that they had made", Mrs Glass said.
When Saturday Comes' memorable cover in 1989 two months after the disaster seems especially pertinent
Mrs Glass also paid tribute to the families who have campaigned for the truth to be revealed behind the atrocity, hailing the findings as "testament to the tenacity of the Hillsborough families' long campaign for truth and justice" and describing their actions as "humbling".
And in a warning to those who face investigation, the statement added the "picture is not yet complete" after a "generation of distress and anger".
Yvette Cooper, the Shadow Home Secretary, said the Hillsborough families are "owed justice"
"No one should ever have to fight as hard and as long as the Hillsborough families had to do simply to get the truth about the death of a loved one. That is not acceptable and should never be allowed to happen again," she added.