An area of north Donegal was sealed off overnight, as gardaí backed up by the Army, searched for a man sought by police in Northern Ireland.
A property near the village of Burnfoot, 8km from the border, was surrounded.
Garda roadblocks were put in place and the public was advised to avoid the area.
At the request of the PSNI, gardaí began searching for Kieran McLaughlin, 58, yesterday.
His photograph had been circulated by detectives investigating the murder of Barry McCrory, 35, in Derry city on Thursday morning.
The PSNI appealed to Mr McLaughlin to make contact with them.
He is described as 1.7m (5'7") tall, of medium build, with blue eyes and grey hair.
Mr McCrory's death occurred less than 24 hours after the body of Kevin Kearney, 46, was found in a lake in north Belfast.
A 39-year-old man has been arrested in connection with Mr Kearney's murder and is being questioned at the Serious Crime suite at Antrim police station.
Tánaiste and Minister for Foreign Affairs Eamon Gilmore described the two murders as vicious, brutal and cowardly.
Police are so far treating the killings as separate incidents.