A man aged 23 has been arrested in connection with the murder in August of Dean Johnson in Clondalkin.
The man is being detained in Lucan Garda station under provisions of section 50 of the Criminal Justice Act 2007 as amended.
Dean Johnson (21) was shot dead at Harelawn Green, Clondalkin, on August 24th last.
Senior officers investigating the murder had said they were shocked at the level of violence used. From the Greenfort area of Clondalkin, not far from where he was shot, he was initially wounded once in the upper body.
When he fell to the ground, the gunman stood over him and fired up to 13 further shots into him, mostly to the head. The gunman, aided by at least two accomplices, used a semi-automatic handgun.
The dead man was known to gardaí, but he was regarded as a low-level operator in the drug trade rather than a major gangland figure.