The man believed to have killed Gavin McShane and Shane McArdle is suspected of involvement in up to 12 murders across north Armagh and east Tyrone at the time.
A close associate of former UVF commander Billy Wright, he is also thought to have been an RUC Special Branch and MI5 agent. Wright's UVF unit has been linked to two Czech-made rifles used to kill almost 20 people between 1988 and 1994.
Members of the security forces are also alleged to have been involved in a large number of these killings.
Four members or the Royal Irish Regiment were questioned about the murder of the teenagers, although no-one has ever been charged.
It has emerged that the weapon used in the attack, a .32 self-loading pistol, was similar to guns given to off-duty members of the security forces for personal protection.
The gun has never been recovered.
A report into the murders recently carried out by Relatives For Justice has identified a number of shortcomings in the police investigation.
These include the fact that clothes worn by Mr McShane have been destroyed by police, ending any possibility of obtaining DNA evidence.
Files relating to the case were also destroyed after police claimed they were contaminated by asbestos at Gough Barracks in Armagh.
Other potential pieces of evidence, including two of the three bullets fired during the attack, cannot be accounted for by police.
Billy Wright, pictured, and Gavin McShane's killer are believed to have been
tipped off that they were named as suspects by family members.
It has also emerged that two men who were seen acting suspiciously on the outskirts of Armagh on the morning of the murders were undercover British soldiers.
Relatives for Justice spokesman Mark Thompson claimed the original police investigation has been characterised by "a series of forensic, ballistic and other significant failings that would warrant a fresh investigation".
Connla Young