There is confusion over whether a soldier who arrived at the scene of a Catholic salesman's murder within minutes of the shooting is still alive, a coroner has been told.
Daniel Carson, from Dunmurry, was shot as he left work at a hardware merchants in the Shankill area of Belfast in November 1973.
No-one has ever been convicted in connection with the sectarian killing, which was attributed to an unidentified loyalist group.
New preliminary inquest proceedings have established that three soldiers from the 1st Battalion The Queen's Regiment were on the scene shortly after the shooting. Two of the soldiers also apparently went to the home of a suspect.
With Mr Carson's family keen for the men to give evidence when the full inquest is convened, a lawyer for the coroner told a preliminary hearing in Belfast that it was not clear whether one of them was dead or alive.
Sean Doran QC, counsel for coroner Suzanne Anderson, said while the Ministry of Defence believe he is dead, a police investigator who reviewed the case said he spoke to him on the phone.
"There seems to be some confusion whether or not one of these witnesses is still alive," he told Ms Anderson.
Peter Coll QC, representing the MoD, said officials would have to investigate the matter further. "This is an issue that we are going to have to iron out," he said.
Mr Doran said there could be a "simple explanation" for the discrepancy, suggesting that the former soldier could have died since he spoke to the investigator from the recently wound-up police Historical Enquiries Team (HET).
Patricia Coyle, representing the Carson family, said if the man was dead the MoD should provide a death certificate to court.
Mr Carson was 29 when he was murdered. His wife Anne was expecting their second child.
His death is among a number of Troubles-related cases being re-examined by the Coroners Service following a direction from Attorney General John Larkin QC in 2012.
An original inquest in 1974 returned an open verdict.
After this morning's hearing, Mr Carson's sister Sile, speaking on behalf of the family, urged any witnesses to her brother's murder to come forward.
"We would ask people to reflect on who my brother was," she said. "This is a new opportunity for them to address what happened then and come forward."
Ms Carson also expressed concern at the time it was taking for MoD and PSNI files to be disclosed to the court.
The family has set up a dedicated number for any potential witnesses to contact them - 00353861089173