The Police Ombudsman is studying more than a dozen police murder investigations spanning the history of the Troubles. This is in addition to several high-profile probes already carried out by Nuala O'Loan's office and a number which are near completion.
The revelation that the Ombudsman is looking at so many 'historic' cases has prompted an expectation that further damning police failures and intentional wrongdoing by officers could be exposed.
Complaints lodged by families of people murdered from the early 1970s to late 1990s are wide-ranging and include claims that their deaths were not properly investigated by police a criticism of unsolved paramilitary killings in the last few years.
The Ombudsman is looking at 15 cases, one a non-fatal paramilitary attack. The cases include three controversial deaths that Mrs O'Loan recently announced her intention to investigate:
- the murder of Protestant Raymond McCord whose family believe his killing was sanctioned by a UVF leader, an alleged police informer, in 1997
- the killing of Catholic RUC officer Joe Campbell outside Cushendall police station in 1977 a case dogged by claims of a possible police conspiracy
- the death of Portadown teenager Alice McLoughlin 12 years ago from a shot discharged from a pistol owned by a serving police officer.
Some files being examined are at the preliminary inquiry stage while detailed investigations into others have already begun.
Last night a spokesman for the Police Ombudsman's office said: "We are considering complaints about 15 retrospective matters.
"Some of these will be complicated and resource-intensive investigations.
"A business case has been submitted to the Northern Ireland Office requesting additional funding to meet the cost of these and discussions are continuing.
"We are reprioritising our resources to allow us to investigate all these cases but some may take longer than originally anticipated."
The Ombudsman has uncovered serious shortcomings by police in a number of cases, most notably the RUC investigation into the Omagh bomb.
The cases do not include the investigation into the murder of Portadown Catholic Robert Hamill in 1997 which Mrs O'Loan is overseeing and the now completed probe into claims that police failed to properly investigate loyalist death threats against solicitor Rosemary Nelson before her murder in 1999.
SDLP representative Alban Maginness said he expected more families to demand to know whether investigations into the deaths of their loved ones were deliberately hampered.