Gardaí investigating the murder of Keane Mulready-Woods earlier this year.
The 17-year-old was killed on 12 January and his body dismembered.
A man in his early 20s was arrested shortly after 7am on Thursday and is currently detained at Dundalk Garda Station.
Another man, also in his early 20s, was arrested shortly after 10am on Thursday and was detained at Mountjoy Garda Station.
He has since been released without charge and a file will be prepared for the Director of Public Prosecutions.
A third man who was arrested on Tuesday 8 December in connection with the murder continues to be detained at Drogheda Garda Station.
Investigations are ongoing.
