Hillsborough victims' families say they are to press for criminal action after a damning report into the disaster.
An independent report into previously unseen papers said police had failed to save lives, altered witness statements and tried to blame Liverpool fans.
Trevor Hicks, whose two daughters died in the 1989 stadium crush, said the state should now put right the wrongs.
South Yorkshire Chief Constable David Crompton said if officers had broken the law, they should be prosecuted.
Speaking to the BBC's Newsnight, he said: "My position is a very simple and straightforward one, which is that if people have broken the law then they should be prosecuted.
"It doesn't make any difference whether they're a police officer or anybody else."
He added: "We will treat this with the utmost seriousness. And then if people have got serious questions to answer, we'll act appropriately."
Mr Hicks said if the state did not start legal proceedings, the families would do it themselves.
"We have two eminent lawyers. They will take the long-term look," he told Newsnight.
"If I come back to David Cameron's statement [to MPs], he said quite categorically that the state had let us down.
"So we will give the state the opportunity to put that right. But if it looks as though they're not going to do that, then we will do as we've done before and we'll take it out of their hands."
Ninety-six Liverpool fans died after a crush on overcrowded terraces at Sheffield Wednesday's ground during the FA Cup semi-final between Liverpool and Nottingham Forest in April 1989.
The report published on Wednesday was compiled by the Hillsborough Independent Panel, which had scrutinised more than 450,000 pages of documents over the past 18 months.
Following its publication, David Cameron apologised to victims' families for the "double injustice", which he said was both in the "failure of the state to protect their loved ones and the indefensible wait to get to the truth", and in the efforts to denigrate the deceased and suggest that they were "somehow at fault for their own deaths".
On the front page of its Thursday edition, the Sun newspaper apologised for its infamous story headlined "Hillsborough: The Truth" which alleged Liverpool fans had picked the pockets of victims, urinated on police and attacked officers trying to save lives.
In a video on its website, current editor Dominic Mohan said the paper was "deeply ashamed and profoundly sorry".
As well as legal action, families and campaigners, including Labour MP for Liverpool Riverside Louise Ellman, are calling for a fresh inquest to be held.
She said the scale of the conspiracy over the disaster was "outrageous".
The families have always challenged the original inquest, which concluded that all the victims had been dead or brain dead 15 minutes after the game had kicked off at 15:00.
By analysing post-mortem test results, the Hilsborough panel found 28 of the 96 victims had had no "obstruction of blood circulation" and there was "separate evidence that, in 31, the heart and lungs had continued to function after the crush".
The medical adviser on the panel, Dr Bill Kirkup, said up to 41 of the 96 who died could have potentially been saved if they had received treatment earlier.
Margaret Aspinall, chairwoman of the Hillsborough Families Support Group, said what the families had gone through was an "absolute disgrace".
"They were the liars and we were the truthful ones," she said.
"It doesn't make us feel better, because we will always be the losers at Hillsborough."
Liverpool fans and relatives of the victims have campaigned for 23 years to find out exactly what happened on the day of the disaster, which saw the biggest loss of life at any UK sporting event.
The report found police and emergency services had made "strenuous attempts" to deflect the blame for the disaster on to fans.
The report found 116 of the police statements identified for "substantive amendment" had been "amended to remove or alter comments unfavourable to South Yorkshire Police".
Mr Cameron said Attorney General Dominic Grieve would review the report as quickly as possible in order to decide whether to apply to the High Court to order a new inquest.
The panel was chaired by the Bishop of Liverpool the Right Reverend James Jones.
He said: "Our job has simply been to oversee the maximum possible disclosure of all the documents and to write a report which adds to public understanding and therefore our terms of reference don't actually allow us to make any recommendation.
"The documents speak for themselves."
An independent inquiry led by Lord Chief Justice Taylor in the immediate aftermath of the disaster found the main cause had been a failure in crowd control by South Yorkshire Police.