NI's Police Ombudsman is to resume investigations into more than 150 historical events where former RUC officers are accused of criminal activity and misconduct.
Investigations were suspended in 2011 after a critical report into the running of the office.
The report found that the independence of the office had been compromised.
Many of the cases involve allegations of security force collusion.
At the time the ombudsman was Al Hutchinson.
The critical report into his office was carried out by the then criminal justice inspector, Michael Maguire, who replaced Mr Hutchinson as police ombudsman in July 2012.
The report said there had been a lowering of operational independence between the ombudsman and the police, and that investigations into historical events should be suspended.
The criticism contributed to the early retirement of Mr Hutchinson.
A follow-up inspection report published on Wednesday concluded that enough improvements have been made for historical investigations to resume.
Dr Maguire said his previous role had given him an "understanding of the issues that needed to be addressed".
"The office has worked very hard over the last year to put some of those issues in a way which repositions the office to be able to recommence these investigations again," he said.
"I welcome the CJI (Criminal Justice Inspection) report because I think it's the first stage in rebuilding confidence in the office and the work that it does."
He said work had been done to make improvements across a range of areas.
"We've recruited a significant number of new staff who have direct experience in major investigations, changed the ways we prioritise cases, introduced thorough investigative process which are subject to ongoing and systemic review and we've developed a consistent approach to communication for the families," he said.
The ombudsman's office has been given £12m to complete more than 150 historical cases over the next six years.
Dr Maguire admitted that the number of cases to examine was "ambitious".
"At the beginning of exercise we will be doing a lot of review work which collects investigative material," he said.
"Many of those cases, in some cases 20 or 30 complaints, can be clustered around a particular core issue and be dealt with on an ongoing basis.
"I think given those two reasons we're in a much better place to be able to look at these cases in a shorter time frame than has been before."
However, the DUP's Paul Givan raised concerns about the re-opening of historical investigations.
He said it had "the potential to once again damage confidence in the ombudsman's office".
"The DUP has consistently argued the police ombudsman should solely focus upon dealing with present day complaints into the PSNI and de-couple it from historical investigations which has marred this office in controversy from its inception," he said.
"As a result of this decision the ombudsman office will become the subject of intense political scrutiny and debate that will only serve to distract from the important oversight role it has for effectively dealing with modern day policing issues. "