Former police officers may have been newly appointed to a unit investigating security force killings, a barrister told an inquest in Belfast.
Frank O'Donohue QC called for the recruitment of independent coroner's investigators to retrieve information about so-called shoot-to-kill incidents involving police in Northern Ireland.
The inquests include the deaths of six people who were shot by the Royal Ulster Constabulary (RUC) in 1982 and the killings of three RUC officers who died in an IRA land mine attack in the same year. Delays in producing "massive" amounts of state files have repeatedly held up hearings, the inquest was told.
Mr O'Donohue, who represented the coroner, noted recent appointments to a police unit handling requests for information.
"Some of the new members of the Legacy Support Unit support staff may well be retired police officers.
"There remains concern on our behalf that the members that have been assigned, that there is insufficient staff and the speed of work is just not what we need at the moment."
A preliminary hearing of the Stalker-Sampson inquests was held on Tuesday in Belfast.
The fatal shootings were previously investigated during the Stalker-Sampson Inquiry, which sought to determine whether the security forces had operated a shoot-to-kill policy in Northern Ireland.
Those investigation reports have never been made public.
Related inquests, which have yet to formally begin, have been held up by repeated delays in the disclosure of state files, including security forces' records.
Northern Ireland's senior coroner John Leckey has been calling for independent investigators to be appointed for some time. The inquest system could be left with two full-time coroners and a number of part-time judges once Mr Leckey retires later this year.
The Stormont House Agreement between politicians in Belfast anticipated a dedicated system for investigating past killings, funded as part of a comprehensive political deal.
Around 3,000 Troubles killings remain unsolved.
Mr O'Donohue said little progress had been made since the pre-Christmas accord.
Much of the legacy unit's work involves assessing whether documents can be released for inquests.
It took over what was previously the responsibility of independent detectives as well as any murder cases which took place prior to 2004, including the Bloody Sunday Investigation and the re-examination of the on-the-run cases.
Dr Tony McGleenan QC, representing the Police Service of Northern Ireland (PSNI), said a significant amount of material had been disclosed following co-operation between agencies involved in the Stalker-Sampson case.
"This has been a massive exercise across multiple government departments, proceeded with diligently and thoroughly.
"It is quite clear that on that issue which you have raised with us we have discharged to the best of our ability."