The weekend killing of Paul Quinn by a group of men at a shed in Co Monaghan close to the Border has given rise to speculation that elements involved in a lucrative fuel laundering and smuggling racket may have been involved in the horrific crime.
Garda detectives locally are believed to be satisfied the attack on the victim was linked to fuel smuggling or laundering.
According to Revenue officials the laundering of diesel has become a multimillion-euro racket in recent years.
Swoops at isolated sheds, in the Republic and the North, have uncovered sophisticated equipment used by smuggling gangs to remove the colouring from tax-rebated fuel so that it can be sold at the higher commercial price for the top-grade product.
A Revenue spokesman in the Republic confirmed yesterday that raids at a number of locations near the Border have led to a shutdown of several illicit fuel "doctoring" plants.
A major illegal diesel laundering plant was also put out of business on the Northern side of the Border near Crossmaglen after a raid by the Revenue authorities in the North.
A similar plant was also raided and shut down near Castleblayney, just a few miles from the scene of Mr Quinn's murder.
Senior Customs officials in the Republic believe that at least five major smuggling syndicates operating along the Border between Louth and Monaghan and Armagh, and Fermanagh and Cavan are the main players.
According to one senior Revenue source, some of the smugglers had recently begun importing raw diesel from continental Europe with a view to completing the filtering process at secret locations in the North and the Republic, close to the Border.
It is also believed some tankers have been fitted with sophisticated laundering equipment, which can remove colouring from the fuel while in transit.
"This business is so big that these racketeers will stop at nothing to make sure they can get as much profit as possible and they are constantly devising ways to beat the law," one senior Revenue source said.
He said the racketeers have been using carefully developed supply routes and it was unusual if there were any "blow-ups" over such outlets.
"They are usually very careful not to trample on each other's corns when it comes to delivering the fuel to unscrupulous filling stations," he said.
The Revenue suspect that fuel laundered in the Border area may be delivered as far south as Cork and Limerick.
However, recent checkpoint inspections and the increased testing of diesel in use in vehicles has reduced the illicit trafficking.
Instead of being sold into the private commercial market, it is believed that a considerable amount of the "doctored" diesel is still being sold to large firms.
The sludge from laundered diesel has cost local authorities in Louth and Monaghan more than €3 million to dispose of in the past two years, according to council officials yesterday.