Garda Donohoe was shot dead during a cash escort back in 2013.
Gardaí have confirmed that representatives of US Homeland Security Investigations are assisting the investigation into the murder of Detective Garda Adrian Donohoe.
US representatives, led by Acting Deputy Executive Associate Director Alysa D. Erichs, met with Acting Garda Commissioner, Dónall Ó Cualáin, in Dundalk Garda Station on Tuesday.
Describing Homeland Security's assistance as "invaluable" to the ongoing investigation, Gardaí have again appealed to the public for any further information.
On Sunday 4 March, it was confirmed that a young man had been charged with Donohoe's murder back in 2013.
27-year-old Aaron Brady from Crossmaglen, County Armagh, had been questioned since 25 February, following his arrest in Dublin.
Brady was the first person to be charged in connection with the death. A second man in his 60s was released without charge.
Garda Adrian Donohoe was 41-years-old when he was shot dead during a cash escort at the Lordship Credit Union in Bellurgan, near Dundalk, on 25 January 2013.
Gardaí have made thousands of enquiries and have viewed more than 20,000 hours of CCTV footage as part of their investigations into the killing.
According to RTÉ News, Brady was remanded in custody and will appear at Cloverhill District Court by video link next week.
Anyone who has, or believes they may have, information is asked to contact Dundalk Garda Station (042) 9388470 or the Garda Confidential Line 1800 666 111.
