Gardaí have described as "a significant development" the arrest and detention in the United States of a suspect in the investigation into the murder of Detective Garda Adrian Donohoe in Co Louth almost four and a half years ago.

The man, who is in his 20s, was arrested yesterday by Immigration and Customs Enforcement (ICE) agents in New York for immigration violations and is currently in custody pending deportation.

US authorities confirmed the detention of "an Irish national" and said he failed to leave the US on expiration of his visa.

The man is wanted here because he failed to turn up in court after he was convicted of charges in relation to a separate matter.

He is due to be arrested and brought before a judge when he arrives back in the country.

Gardaí will also seek to question him in connection with the murder of Detective Garda Adrian Donohoe who was shot dead while on a cash escort at the Lordship Credit Union in Co Louth on 25 January 2013.