An Irish man suspected of involvement in the murder of Garda Adrian Donohoe four years ago was arrested at Dublin airport on Wednesday morning.
The man, who is from south Armagh and is in his late 20s, was deported from the United States after being detained by immigration officials in New York.
The man, who cannot be named for legal reasons, was detained last Thursday by Homeland Security on allegations he overstayed his visa in the US.
It is understood he was held over the weekend in New York at the Hudson County Correctional facility before his deportation.
A spokeswoman for the Garda confirmed they arrested a man at Dublin airport early Wednesday morning on foot of a bench warrant for a separate matter.
Det Garda Donohoe, a father of two, was shot dead on January 25th, 2013, while on a cash escort with his colleague Det Garda Joe Ryan near Dundalk, Co Louth.
The man who was arrested in New York fled Ireland along with other associates following the murder, over which he is the chief suspect.
It is understood the man had been working in the construction industry in New York and hiding out in the Irish community.
The suspect was detained by the Immigration and Customs Enforcement agency, a branch of the department of homeland security, for violating immigration rules.
It is understood the arrest was made as part of a targeted operation following co-operation between gardaí and immigration officials in New York - effectively side-stepping the extradition process.
Garda Donohoe was on a cash escort at Lordship Credit Union in Bellurgan, Co Louth, with Garda Ryan when they were ambushed by a cross-Border gang.
They opened fire with a shotgun when Garda Donohoe went to investigate a suspicious car.
The five-man gang shot Garda Donohoe dead and then stole more than €4,000 in cash before making their getaway in a Volkswagen Passat.
