This now includes the savage slayings of Ballybough men Joseph Redmond (25) and Anthony Burnett (31) -- the two men who were shot and burned in a forest near Dundalk, Co Louth on Wednesday night.
The 'Taliban' murder gang -- made up of two brothers from Coolock and a 30-year-old north Dublin hood -- are known as some of the most dangerous men on the gangland scene.
The criminals have spent much of the last two years based in Northern Ireland and are key members of a north Dublin gang who are in a separate feud with a Real IRA faction.
The gunmen who are being linked to the Dundalk double murder are also the chief suspects for another savage gangland double slaying.
Glen Murphy (19) from O Devaney Gardens and Mark Noonan (23) from Drumalee -- both in the north inner city -- were shot dead outside a service station at Tesco Express at the Clearwater shopping centre in Finglas in November, 2010.
The killers, who are also closely linked to at least three other separate murders on the capital's northside, fled to Northern Ireland immediately after the cold-blooded executions of the innocent cousins.
The hitmen are considered to be among the most "dangerous and reckless" criminals in Ireland.
They have also been linked with the murder of small time criminal James Perdue (22) who was shot dead in Donaghmede in June, 2006, as well as the evil murders of innocent men Warren O' Connor (24) who was stabbed to death in January, 2010 and Keith Fitzsimons who was gunned down in June, 2006.
Investigators are now trying to establish if they were paid by associates of Michael Taylor Snr to avenge his shocking murder at a caravan park in Donabate during the June Bank holiday weekend last year.
Investigations are today continuing into the savage slayings of Ballybough men Redmond and Burnett who were both small time criminals.
The Herald has previously revealed that one of the strongest theories for the double murder is that the junkie duo were murdered after being blamed for murdering Michael Taylor Snr (53) at a north Dublin caravan park last June.
Officers are also probing whether the double murder is linked to an incident in which the girlfriend of a major north Dublin criminal was attacked during a hold-up.
The hitmen's feud with the Real IRA faction kicked off when a close associate of the notorious RIRA gang was savagely assaulted in a popular north Dublin nightclub.
The violence unfolded when a Donaghmede man who is closely linked to the dissident Republican gang was left with serious injuries after getting in a fight with a senior drugs trafficker outside the well known club.
This drugs trafficker has close links to the suspected hitman team.
A key part of the investigation is the examination by the PSNI of two cars that could have been used in the double murder.
One of the abandoned cars, a silver Mercedes, was found in the Jonesboro area of south Armagh shortly after the murders. It had a Dublin registration plate.
The second vehicle, a Peugeot, was discovered in the same area on Friday afternoon.