A coroner is to consider whether he will allow the identities of two suspects in the murder of 10 Protestant workmen at Kingsmill to be revealed.
Ten men were murdered in south Armagh on January 5 1976 in an atrocity attributed to the Provisional IRA. No-one has ever been convicted.
All the suspects named in documents related to the shooting are referred to by ciphers to protect their identities.
Two of the suspects, referred to during a long-running inquest as S37 and S97, have since died. Some of the families of those killed at Kingsmill have asked that they be named.
Counsel to the coroner Sean Doran said the use of ciphers for the names of suspects has "enabled disclosure of a broad range" of material in the inquest proceedings.
He said work around naming of suspects can be completed by the date of the next hearing.
"After the hearing on October 17, you will have all of the information and all of the submissions you need as to whether or not those two individuals should be named," Mr Doran told the coroner.
Coroner Brian Sherrard said he will consider the request and deliver a ruling.
Mr Sherrard described the matter as "multi-layered", and said he plans to consider all the references in the disclosed documents.
He told the inquest he would consider the matter "in the round", but he had concerns, including the risk of "jigsaw identification" if the two dead suspects are named.
Monday's preliminary inquest also heard that the Coroners Service is hopeful of receiving more material from the Garda before the next hearing later this month.
However, Alan Kane, who represents a number of the families of the Kingsmill victims, voiced his "continuing scepticism".
He accused the Irish state of putting the coroner's requests for information "on the long finger again".
"It [the long finger] seems to me to be like Pinocchio's nose – always growing," he told the inquest.
Mr Kane said that since the first request in 2014, there have been two taoiseachs, three ministers of justice, three ministers for foreign affairs and four Garda commissioners.
He said all made "wonderful statements" assuring co-operation, but there appeared to an "institutional reluctance" to hand over material.
Mr Sherrard said he was anxious to reassure the families that he appreciated their concerns.
Mr Doran pointed out that the inquest has been in communication with the Irish authorities throughout the proceedings, and has received folders of material from the Garda.
The textile workers were shot when their minibus was ambushed outside the village of Kingsmill on their way home from work.
Those on board were asked their religion, and the only Catholic was ordered to run away.
The killers, who had hidden in hedges, forced the 11 remaining men to line up outside the van before opening fire.
Alan Black was the sole survivor.
The next preliminary inquest is scheduled to sit on October 17.
