Gardaí have detained four people overnight in connection with the murder of Jamie Tighe Ennis.
The 24 year old from Artane was shot dead in Coolock in North Dublin in October last year.
Three men aged in their 20s, 30s and 50s were arrested yesterday in the Dublin area.
The fourth person detained by Gardaí is a teenage boy.
All four are being detained at Garda stations across north Dublin.