A father and son are still being questioned by gardaí investigating the murder of Detective Garda Adrian Donohoe in Co Louth last month.
The arrested men - one in his 30s and one in his 70s - were detained after six locations in Dundalk were searched.
Officers say the men were not directly linked to the case, but it is believed gardaí are investigating whether they have been involved in procuring and handling stolen cars for local criminals, including criminal gangs.
Four weeks ago tonight, Garda Donohoe was gunned down during the robbery of Lordship Credit Union in Co Louth.
Chairman of St Patrick's Gaelic Football Club where Adrian played and coached, Alan Duffy, said det Donohoe cannot be forgotten.
"As well as being a brilliant father and husband and a fantastic son and brother to his family, Adrian was a wonderful friend to us all, a brilliant GAA coach and a fantastic mentor to all our children," he said.
"People need to not forget about Adrian. He can't be forgotten."