A man has been arrested in connection to the armed robbery at Lordship Credit Union in 2013.
Detective Garda Adrian Donohoe was shot dead while on escort duty at the Credit Union eight years ago.
The man in his 30s was arrested this morning and charged with offences related to the robbery.
He is being detained at Dundalk Garda Station and is due before Dundalk District Court later this morning.
A second person was also arrested this morning in London, in connection with the same incident.
Last year, 30 year old Aaron Brady from Crossmaglen County Armagh was sentenced to life in prison for the murder of Adrian Donohoe.
He was also sentenced to 14 years in prison for the armed robbery at Lordship Credit Union.