Two men were arrested in Mayo on Tuesday last in connection with the death of a 24-year-old man in England.
The suspects were arrested at an Airbnb property in the Carracastle area.
The men, who are both reported to be from the north Cumbria area, were arrested as part of the ongoing investigation launched following the death of Carlisle man Ryan Kirkpatrick.
Both men appeared before the High Court on Wednesday morning and were subsequently extradited to the UK.
Detective Chief Superintendent Dean Holden said: “This is a significant development in our investigation.
“In order for us not to compromise legal proceedings the names of those arrested will not be released at this time – and we would urge the public not to speculate on social media.
“We continue to encourage anyone with information regarding the death of Mr Kirkpatrick to come forward.
“We believe there are still people out there who can help who have yet to make themselves known,” he added.