The Derry-based Pat Finucane Centre (PFC) is to “disengage” from the Historical Enquiries Team (HET) on cases involving British army killings.
The move follows the publication of a critical report into the way the HET investigated army killings during the Troubles.
Paul O’Connor, of the PFC, was speaking after a police watchdog said the HET investigated cases where the state was involved with “less rigour” than others.
HM Inspectorate of Constabulary (HMIC) said it appeared the HET policy was based on a “misrepresentation of the law”.
It said the HET’s approach was inconsistent and had serious shortcomings. HET was set up in 2005 to re-examine 3,260 murders.
The report also concluded that the HET’s approach to cases involving the state was inconsistent with the European Convention on Human Rights.
Asked if HET had acted outside of the law, Her Majesty’s Inspector of Constabulary, Stephen Otter said: “We think it was acting unlawfully in regard to state cases because it treats them differently in policy terms and in the way that then acts out in practice.
“So state cases were less effective as a result and effectiveness is a key test of whether it’s Article 2 compliant.”
HMIC said the HET risked undermining the confidence of the families of those who died during the Troubles in its effectiveness and impartiality.
PSNI Chief Constable Matt Baggott ordered the review following criticism of the HET in a University of Ulster report.
The report, by Dr Patricia Lundy, claimed the HET gave former soldiers preferential treatment and did not properly investigate deaths caused by the military.
The HET rejected the claims in her report.
Responding to the HMIC report, Dr Lundy said: “I think the HET as an organisation itself is irretrievable at this point.”
Paul O’Connor said the PFC would now be “disengaging from the HET on those cases involving British Army killings”.
“We are advising families that we don’t have confidence in the processes that exist in this point in time,” he said.
“There is something terribly broken here, I don’t know if it can be fixed.
“We are absolutely disengaging on those cases involving British Army killings; on the other cases that is going to be a case by case decision, but the families need to be involved in that.”
Chief Constable Matt Baggott said that all military cases investigated by HET will now be re-examined.