Former Chief Constable Sir Hugh Orde has hit out at the "destruction" of the PSNI's Historical Enquiries Team (HET), which he helped set up.
Sir Hugh claimed that the resolution of controversial legacy cases could have been much easier if the investigating body had not been closed down.
His comments came in the first week of a two-week review of outstanding Troubles inquests, during which Lord Justice Weir expressed frustration over delays and postponements.
Justice Weir is looking at why 56 cases covering 95 deaths are yet to be heard. They include killings by paramilitaries and security forces, many involving claims of collusion.
Sir Hugh said cases must be looked at "in a different way" and branded the "destruction" of the HET a "massive mistake" with huge consequences.
The body was disbanded in 2014 as a result of cuts and after a report by Her Majesty's Inspectorate of Constabulary (HMIC), led to the HET's director, Dave Cox, resigning.
Speaking to the online policing magazine PoliceOracle.com, Sir Hugh said: "The past needed to be looked at in a completely different way. HMIC's destruction of that unit was a massive mistake in my judgment. It was short-sighted."
In 2013 a HMIC report into the HET said the body investigated cases where the state was involved with "less rigour" than others, adding it appeared the HET's policy was based on a "misrepresentation of the law" and that its approach was inconsistent and had serious shortcomings.
The HET was disbanded when the PSNI was forced to close more than 300 agency posts due to budget cutbacks.
Earlier this week, Justice Minister David Ford said the money agreed by politicians at Stormont to deal with the past should be immediately released to help deal with the backlog of legacy inquests.
A failure by politicians to agree mechanisms to deal with such issues has meant that initiatives, including more support for the Coroners Service, have yet to get off the ground.
Just 13 legacy cases have been heard in 10 years, with the time taken by police to security-vet classified case files highlighted as a main cause of delays.