A new report into the Omagh bomb investigation is believed to hold out the hope that the killers can still be caught.
The investigation, by Merseyside Deputy Chief Constable Mike Tonge, is also expected to confirm mistakes made at the time have now been sorted out.
One source close to the report, due out today, said: "He has quality-assured the ongoing inquiry and has found that all the weaknesses have been ironed out. Proper procedures are now in place and he's hopeful people will still be arrested".
Mr Tonge and another top Merseyside officer, Mr Phil Jones, were called in after a bitter dispute broke out over how the Royal Ulster Constabulary investigated the August 1998 "Real IRA" bombing that killed 29.
None of those responsible for the biggest single atrocity in the Northern Ireland conflict has been charged with any of the murders.
A scathing assessment issued by Police Ombudsman Ms Nuala O`Loan last year said Special Branch officers were warned that dissident republicans planned to target Omagh but failed to alert officers on the ground. Her report also accused former RUC Chief Constable Sir Ronnie Flanagan of defective leadership.Sir Ronnie strenuously defended his record and the efforts of his senior officers to hunt down the bomb team.
In a bid to defuse the row and reassure relatives of those killed in Omagh, the police board called in Mr Tonge last May to monitor and report on progress in the investigation.
The Merseyside officer also examined resources and skill levels and moves to enhance working practices with the Garda Siochána.