The extent of PSNI involvement in the arrest and questioning of two documentary makers has prompted questions over the independence of the investigation.
Lawyers for journalists Trevor Birney and Barry McCaffrey have expressed concern about the Police Service of Northern Ireland's role in what was portrayed as a Durham Police operation.
They claim the events in Belfast last Friday were dominated by local officers throughout.
The award-winning journalists were released on police bail on Friday evening after being held for 14 hours for questioning over the alleged theft of confidential material from a police watchdog.
The PSNI originally asked Durham Police to conduct the investigation into how material held by the Police Ombudsman for Northern Ireland ended up in the reporters' documentary on the notorious Loughinisland massacre of 1994.
With the No Stone Unturned film exploring persistent claims of security force collusion with the loyalist paramilitaries who murdered six men in the Co Down village, PSNI chief constable George Hamilton called in an external force to probe the theft allegations, citing potential conflict of interest concerns.
But solicitors Niall Murphy and John Finucane, who represent Mr Birney and Mr McCaffrey respectively, have now questioned the stated independence of the Durham inquiry, insisting the PSNI had a prominent role throughout Friday's events.
The concerns outlined to the Press Association include:
- Both lawyers say the multiple custody interviews with their clients involved one Durham detective and one PSNI detective, with the local officers asking as many questions as the English ones.
- Mr Murphy claims only three Durham officers were in Belfast for an arrest and detention operation that he said involved more than 100 PSNI officers in total.
- Mr Finucane says he only had contact with one Durham officer throughout Friday.
- Mr Finucane says the warrant to search Mr McCaffrey's home was a PSNI warrant, supported by PSNI evidence.
- Both solicitors say the officer supervising the logistics of the interviews - outlining the extent of evidence disclosure and when each taped session started and finished - was a PSNI officer.
- The men say a PSNI sergeant also bailed their clients and set the attached release conditions.
Mr Murphy said: "In my respectful opinion, this arrest and interview strategy was overwhelmingly directed and executed by officers of the PSNI."
Mr Finucane said he was concerned at the extent of PSNI involvement.
"In relation to Mr McCaffrey I only had interaction with one police officer from Durham, after that it was exclusively PSNI," he said.
"Since the arrest on Friday I have now material in relation to the warrant to enter and search Mr McCaffrey's home - that was granted on the basis of a PSNI application and supported by PSNI evidence."
The six men murdered when Ulster Volunteer Force gunmen opened fire inside the Heights Bar in Loughinisland in June 1994 were football fans who had gathered to watch the Republic of Ireland play in the World Cup.
The 2017 documentary by Mr Birney (51) and Mr McCaffrey (48) broke new ground by publicly naming those it said were suspects.
The PSNI declined to comment when asked whether the level of its participation in the men's arrests and detention was appropriate.
The service instead referred questions to Durham Police.
A spokesman for Durham Police said Northern Ireland police involvement was appropriate, insisting they only played a "supporting role".
"Two men were arrested on Friday as part of a Durham Constabulary-led investigation into the suspected theft of confidential documents from the Police Ombudsman For Northern Ireland," he said.
"Both men were questioned by Durham Constabulary officers at Musgrave police station in Belfast and were released on bail, pending further enquiries.
"This is an independent investigation, led and shaped by Durham Constabulary, in which all operational decisions are made by our officers, assisted when deemed necessary by an appropriate level of resources from PSNI in a supporting role".
Detectives are examining phones, computers and documents seized from the journalists' homes during Friday's early morning raids.
A High Court challenge by the film company behind the documentary has prevented the police from examining material seized at a separate search at its Belfast offices last week pending a full court hearing on Friday.