Crime boss Cyril 'Dublin Jimmy' McGuinness - who was the prime suspect for organising the abduction and torture of QIH executive Kevin Lunney - once threatened to shoot the suspected 'paymaster' who hired him to carry out the campaign of violence against the former Quinn companies, it is claimed.
It can be revealed that the violent gangster, who suffered a fatal heart attack when police raided his safe house in Derby last Friday, accused the financier of trying to rip him off when he failed to pay up following one particular series of arson attacks and other acts of criminal damage against the new owners of the Quinn group a number of years ago.
Security sources revealed that the incident arose after McGuinness, who had been receiving regular payments for the ongoing attacks, flew into a rage when the agreed fee hadn't been delivered by the 'paymaster's' intermediary.
It is understood that at the time armed gardai were rushed to protect the secret financier at his home after receiving a tip-off believed to have been from the PSNI.
When informed his life may be in danger, the 'paymaster' is understood to have made a phone call and later told gardai the threat did not exist and the security operation was stood down.
Garda intelligence sources later revealed that McGuinness withdrew the threat when the paymaster explained there had been a "mix up" and the money was paid.
However the falling out proved to be short-lived and Dublin Jimmy continued waging the campaign of violence which steadily escalated over the past two years, culminating in the horrific attack on Kevin Lunney, one of the five QIH directors whose lives are still under threat.
Gardai believe that McGuinness, who had earned millions from organised crime, was paid in excess of €1m for carrying out the attacks on the former Quinn companies over the past eight years, and was in line for another major payment for the latest attack.
But Dublin Jimmy's untimely death and the seizure of valuable evidence in the form of documents and electronic devices found in his UK bolthole has dramatically tightened the garda net around the 'paymaster' and the gang responsible for the Lunney attack.
It is understood that McGuinness' gang and associates are in disarray, with one security source revealing: "They are watching the media stuff and it has them all running around like scared rats at the moment and some of them are more panicked than the others.
"Now that the full might of the State is behind it, they (the gang) have good reason to fear that they will be facing very serious charges."
Gardai say that since the attack in September they have been receiving considerable co-operation from the public which is likely to increase now that the spectre of Dublin Jimmy has gone from the border region.