A man is due to appear in court in Blanchardstown in Dublin in connection with the Dean Johnson Murder investigation.
21-year-old Dean Johnson was shot dead in a brutal killing close to his home on the Neilstown Road in Clondalkin.
The gangland-style hit took place in the early hours of Saturday August 24.
He had only one previous conviction for a driving offence, but it is understood he was known to gardaí.
Last week two men were arrested in connection with his murder following a number of planned searches in Ronanstown, Clondalkin, Cabra and Kilcock in County Kildare.
Gardai say a man in his 20s is now scheduled to appear before Blanchardstown district court following the discovery of a firearm during the raids.