Manslaughter investigations could be launched after a damning report into the Hillsborough disaster revealed an orchestrated police cover-up.
The Chief Constable of South Yorkshire Police, David Crompton, has said the force is considering asking a police watchdog whether officers involved in the tragedy should face criminal charges.
He said the force - which is at the centre of the cover-up - was looking into a number of issues to refer to the Independent Police Complaints Commission (IPCC), including corporate manslaughter, manslaughter and misconduct in public office.
"I do wish to make it absolutely clear that, although we haven't worked out the full details yet, there will be a referral to the IPCC in the next couple of weeks. That is not in any doubt," he said.
Meanwhile, the Chief Constable of West Yorkshire Police apologised for any upset caused by his statement on Thursday, in which he said Liverpool fans' behaviour made policing at the tragedy "harder than it needed to be".
Sir Norman Bettison, who was the most senior serving officer involved in the discredited South Yorkshire Police investigation, said his role was never to "besmirch" fans who "were in no way to blame for the disaster that unfolded".
The Hillsborough Independent Panel, which had access to 450,000 documents, found that 164 police statements were doctored, 116 of them to remove or alter "unfavourable" comments about the policing of the match and the unfolding disaster.
Ninety-six Liverpool fans died in the crush at Hillsborough Stadium on April 15, 1989, during an FA Cup semi-final tie between the Merseyside club and Nottingham Forest.
Speaking at a South Yorkshire Police Authority meeting in Barnsley, Mr Crompton said: "Clearly, there may be potential for corporate manslaughter, given some of the detail which came out the other day.
"That relates, of course, to how things were handled on the day and the view taken about the 3.15pm cut-off point.
"In addition to that, there may, again potentially, be the possibility of manslaughter investigations against individuals.
"Again, these are only potentials, these are things we are looking at the moment. I'm not saying that these are definitely things which are to be referred to the IPCC.
"In relation to alteration of statements, which has received a great deal of publicity this week, clearly, that is something that we are looking very closely at. It's highly likely that that will form part of the referral to the IPCC."
Mr Crompton went on: "The other areas that we will be considering referring to the IPCC will be issues of misconduct in public office, also leaking information to the media, issues to do with the data protection act in relation to some of the checks that were done on the Police National Computer."
Families of the victims have vowed to carry on their fight by pursuing criminal prosecutions against those who they said should "hang their heads in shame".
They have already called for a fresh Hillsborough inquest and for the verdicts of accidental death to be overturned - a process being considered by Attorney General, Dominic Grieve, which could take weeks or months.
Trevor Hicks, from Keighley, West Yorkshire, who lost two daughters in the tragedy and is president of the Hillsborough Families Support Group, said relatives would not speculate on what charges should be brought before they had reviewed the evidence.
He added: "David Crompton is the first chief constable who has ever actually done anything about Hillsborough and we commend him for it and we thank him for it."
Deborah Glass, deputy chairman of the IPCC, said the report raised "extremely serious and troubling issues for the police".
"Clearly there is a huge amount of information contained within the report and supporting documentation that needs to be analysed and digested.
"We are reviewing the panel's report and we are aware that South Yorkshire Police are also carrying out a detailed assessment of the report with a view to making a referral to the IPCC.
"We also await the decision by the Attorney General in respect of the inquests, and will liaise with the relevant parties to identify what should be investigated, and by whom."