A murder inquiry into the Bloody Sunday killings in Derry is to begin in the new year.
Senior commanders from the PSNI today briefed relatives of the 14 people who died after British paratroopers opened fire on civil rights demonstrators in the city in 1972.
Earlier this year, police signalled an intent to investigate the incident after they and prosecutors reviewed the findings of the Saville public inquiry into the controversial shootings.
Until today it had been unclear when such a probe would start.
After the 12-year inquiry, Lord Saville found that the killings were unjustified and none of the dead posed a threat when they were shot.
That contradicted the long-standing official version of events, outlined in the contentious 1972 Widgery report, which had exonerated soldiers of any blame.
The Saville Inquiry prompted British Prime Minister David Cameron to apologise to the relatives.
Thirteen people died on the day, with a badly injured man dying a number of months later.
PSNI Deputy Chief Constable Judith Gillespie and Assistant Chief Constable Drew Harris outlined details of the murder investigation to the Bloody Sunday families in the city this morning.