A second man has been arrested in connection with the murder of Detective Garda Adrian Donohoe in Co Louth five years ago.
The man in his 50s was arrested in Dundalk late yesterday. He is currently being detained at Balbriggan Garda Station.
A 28-year-old man who was arrested as he left Wheatfield Prison on Sunday evening remains in custody.
He was taken to Dundalk Garda Station, where he can be questioned for up to three days.
Gardaí are expected to make a court application today to extend his detention period for a further three days.
Det Donohoe, a father-of-two, was shot dead outside Lordship Credit Union in Bellurgan in Co Louth on 25 January 2013.
He and a colleague, Detective Garda Joseph Ryan, were on a cash escort from a number of credit unions on the Cooley Peninsula when an armed gang blocked them in to a car park outside Lordship Credit Union.
When Det Donohoe got out to investigate, two gunmen ran towards him and one shot him dead.
Det Ryan was then held at gunpoint by two of the raiders while the others robbed cash and other items from the credit union employees.
Earlier this year, gardaí said the suspects for the murder were known to them. They have described the developments over the past two days as significant.