No one has been convicted for the Omagh murders
The police are examining the possibility of a retrial of a South Armagh man cleared of involvement in the Omagh bombing.
The revelation came during a meeting of the Northern Ireland Policing Board on Thursday.
South Armagh man Sean Hoey was cleared of murdering 29 people in Omagh, at the end of his trial in December 2007.
The trial judge seriously criticised the police handling of evidence, and said two officers had lied.
However, an investigation by the Northern Ireland's Police Ombudsman concluded there was no evidence to support the claim the officers had lied and questioned the defence team's claim that the evidence from Altmore Forest had been wrongly handled.
Assistant Chief Constable Drew Harris told the board that police have been "reviewing the entire case."
"After the ombudsman reports of February this year we have revisited all of the evidence again, not only in respect of the Omagh bombing but other bombing attacks around that time involving the Real IRA," he said.
"Working through that what we are looking for is new evidential opportunities, realistically we have to find substantial new evidence if there is any possibility of a criminal prosecution."
When the review is completed, it will be up to the Public Prosecution Service to decide if there is enough evidence to merit a new trial.