The guns used to kill Sam Marshall were from a haul smuggled into Northern Ireland by a top security force agent, the murdered man’s family has claimed.
Brian Nelson was a leading member of the loyalist Ulster Defence Association (UDA) and a prized asset of military intelligence.
He has been linked to a string of controversial killings, including the murder of Belfast solicitor Pat Finucane in 1989.
The HET (Historical Enquiries Team) was unable to answer all the questions posed by relatives over the weapons used in the Sam Marshall murder.
But the family obtained a copy of the original RUC (Royal Ulster Constabulary) report on the killing, after the document was handed to a US court as part of an extradition case in 1993.
* It confirmed the guns were VZ58 automatic rifles, similar in appearance to the infamous AK47 weapon.
* Victims groups have said the rifle model was among a consignment smuggled into Northern Ireland for use by loyalist paramilitaries in the late 1980s with the help of Brian Nelson.
* The rifles formed part of a major arms shipment from South Africa and the entire stockpile has been linked to 95 of the estimated 225 loyalist murders carried out in the six years following the arrival of the cache.
The family further claimed that by comparing information with other victims of loyalist violence, they have directly linked the guns that killed Sam Marshall to four other murders and an attempted murder.
The Marshall family has also questioned whether the description of a man seen acting suspiciously near Lurgan police station on a previous bail signing by the three republicans matched that of Robin Jackson.
The leading UVF member, known as "The Jackal", featured in a recent HET report on the murder of members of the Miami Showband pop group in 1975, which pointed to collusion by security forces.
The HET said attempts by the RUC failed to link the description of the man seen in Lurgan to known loyalists.
Rosemary Nelson, a Lurgan solicitor who took up the Marshall family's case, was killed by loyalists in 1999 amid allegations of state collusion.
An inquiry said the state was not directly linked to her killing, but it could not rule out involvement by rogue security force members and it was heavily critical of the RUC and government.
It concluded Mrs Nelson's life was threatened by RUC officers, that police assaulted her in public, and leaked intelligence — all of which contributed to making her a target.
PA