One of the guns used in the 1976 Kingsmills massacre was also used in the murders of two senior police officers in 1989, an inquest has heard.
The inquest into the IRA murder of 10 Protestant workmen is continuing at Belfast Coroners’ Court.
It has been hearing from a police intelligence officer, known as J2.
On Tuesday, he told the inquest the 11 guns used in the Kingsmills attack had been used in over 40 serious terrorist incidents in a 15-year period.
One of the weapons, an Armalite assault rifle, had first been used in the murder of two soldiers from the Parachute Regiment in March 1974.
The same weapon was used 15 years later, in March 1989, in the murders of Ch Supt Harry Breen and Supt Bob Buchanan in south Armagh.
Ch Supt Breen was the most senior RUC officer killed during the Troubles.
In all, four Armalites, two rifles, a semi automatic rifle, a carbine, a sub-machine gun, a shotgun and a revolver were used in the Kingsmills massacre.
‘Close-knit group of terrorists’
Officer J2 stated it was clear the weapons had been used in a “reasonably localised general area” in murders, attempted murders and other gun attacks, for which some people were later convicted.
The inquest was told one small close-knit group of terrorists in south Armagh may have been using the weapons for a time.
J2 added that it was the PSNI’s current assessment that the Provisional IRA carried out the Kingsmills murders, using the cover name of the South Armagh Republican Action Force.
On Monday, the inquest was told that 13 suspects are listed in security documents linked to the 1976 massacre.
The 10 workmen were shot dead on 5 January 1976 after the gunmen stopped their van and asked which among them was a Catholic, and instructed that man to leave the scene.
No-one has ever been held to account for the murders.
The inquest was halted in June 2016 after just a month, and after hearing evidence and statements from 53 witnesses.
The adjournment came after the PSNI arrested a man in connection with the murders.
That followed the discovery that a left palm print was recovered from a window of a vehicle used by the attackers.
It is understood the print matched the man arrested in the Newry area.
Earlier this year the Public Prosecution Service decided not to prosecute the man, saying the test for prosecution had not been met.