Police in Ulster are to launch a murder enquiry into the Bloody Sunday massacre in Derry 40 years ago.
The British government has confirmed the investigation into the 14 deaths when British paratroopers opened fire on a civil rights demonstration.
The Police Service of Northern Ireland (PSNI) will conduct the murder enquiry according to Irish state broadcaster RTE.
Senior officers have already briefed relatives of those who died.
Their murder enquiry follows an in-depth review of the Saville public inquiry into the controversial shootings.
The Saville report found that the killings were unjustified and none of the dead posed a threat when they were shot.
The findings contradicted the long-standing official version of events as outlined in the contentious 1972 Widgery report which had exonerated soldiers of any blame.
British Prime Minister David Cameron apologised to the relatives in the wake of the Saville report.
PSNI Deputy Chief Constable Judith Gillespie and Assistant Chief Constable Drew Harris outlined details of the murder investigation at a press conference in Derry.
The confirmed that the investigation will be ‘lengthy and complex’ and is expected to last at least four years.
The PSNI also stated that statements given by witnesses to the Saville Inquiry cannot be used as evidence in criminal proceedings.
They have appealed those people who made statements to Saville to come forward again to make official statements.
A PSNI spokeswoman said: “Senior police met a delegation in Derry representing some of the victims killed on Bloody Sunday.
“Following consultation earlier this year with the Public Prosecution Service, officers provided an outline of the processes involved and the challenges posed by a criminal investigation into the events of 30 January 1972.
“The delegation was informed about the appointment from Serious Crime Branch of a senior investigating officer and the allocation of resources to create an investigation team which will begin work in the New Year.
“For the investigation to be as comprehensive and effective as possible, police will be asking for public support in the form of witnesses who gave evidence to the Saville Inquiry now making statements to detectives.
“This is because police are precluded from using Saville testimony in a criminal investigation. Details on how this process will be facilitated will be made available in the near future.
“Police have also undertaken to provide updates to surviving victims and all the families who lost relatives on Bloody Sunday through the course of the investigation which will be lengthy and complex.”
Northern Police Ombudsman Dr Michael Maguire has also accepted a court direction that his office should set aside its public report into aspects of the terrorist attack on Loughinisland in 1994, which was issued in June 2011.
The ombudsman said: “In the light of the Judicial Review proceedings instigated on behalf of Brigid Green, Dr Maguire commissioned a review of the content of the report.
“Having considered the findings of that review, he accepts that there may be deficiencies in specific areas of the report and is therefore able to accept the court direction setting it aside.”