Gardaí say this latest suspect is being held at a Garda station in west Dublin.
A third arrest has been made in connection with the death of a man at a restaurant in West Dublin on Christmas eve.
Tristan Sherry died during a botched shooting after he walked into Browne's Steakhouse on the main street in Blanchardstown on Christmas eve and shot a man.
He was then tackled and stabbed as he tried to escape.
He was pronounced dead at the scene.
Last Saturday, 22-year-old Michael Andrecut, with an address at Sheephill Avenue in Dublin 15, was charged with his murder.
Yesterday Gardaí detained a second person in connection with Mr. Sherry's death.
He is still being questioned.
Now a third arrest has been made.
Gardaí say this latest suspect is being held at a Garda station in west Dublin.

HSE Say Some Records Accessed During Cyber Attacks
Jozek Puska Abandons Murder Conviction Appeal
Maynooth University Hosting European University Initiative Forum As Part Of EU Presidency
Gardaí Seize €2M Of Cannabis-Infused Products In Five Counties
Dublin Man Sentenced To 14 Years In Hungarian Prison For Murder Of American Woman
Man Lay On Street For Two Hours With Serious Head Injuries After Alleged Assault In Dublin, Court Hears
Rate Of Inflation Down Slightly In June
Gardaí Renew Information Appeal After Serious Crash In Laois Last Month