A specialist team has begun to review unsolved murders committed during the Northern Ireland Troubles.
Dave Cox and Phillip James of the HET
The Historical Enquiries Team, which has a budget of more than £30m, will re-examine 3,268 killings between 1969 and the 1998 peace accord.
The squad of about 100 detectives and support staff will need between five and seven years to complete its work.
Northern Ireland's Chief Constable, Sir Hugh Orde, said he hoped it would bring closure to many families.
"The families have a right to know as much as we can tell them," he said.
"If there are lines of inquiry to follow which gives us an opportunity to go to court, that team will deliver against that.
The review team, led by retired Metropolitan Police Commander David Cox, will use the latest forensic science and intelligence analysing technology.
Mr Cox said the team's two main aims would be to "offer answers and a greater level of resolution to bereaved families".
"I do not for a moment underestimate the complexity of this challenge or the potential emotional stress for relatives associated with re-visiting these tragic events," he said.
"That is why families will sit at the very heart of our investigations, and that is why our primary objective will be to work with them to achieve some measure of resolution for them."
There will be two distinct investigative units - one will be made up exclusively from officers from outside Northern Ireland, who would work on cases, where, for example, there had been allegations of security force collusion.
The team said they would be operationally independent from the PSNI, but would report to the chief constable.
The Northern Ireland Secretary, Peter Hain, said it was quite possible that people would serve jail terms as a result of the new murder investigations.
He told the BBC some of the murders involved members of the security forces and all would be investigated thoroughly.
"We're dealing with some of the most horrific circumstances ever in Northern Ireland's troubled history, the worst.
"Twenty, 30 years ago, things were done which should not have been done, either by terrorists or in some cases - a limited number of cases - by members of the security forces. All of them will be investigated and there will be closure on them."
The BBC's Ireland correspondent Kevin Connolly said the relationship between republicans and unionists is not good enough for a Truth and Justice Commission.
Inquiries focusing on the 30 years of the Troubles are long and expensive, he added - Lord Saville's inquiry into Bloody Sunday has taken seven years and cost more than £150m.
Mr Connolly said: "Some way has to be found to deal with the many issues from the past that dominate the day-to-day political agenda.
"The cold case team is the government's latest answer."
Work on the first 100 cases is due to begin on Monday.