A 48-year-old Lithuanian man who was assaulted in Dublin on Saturday night remains in a critical condition on a life-support machine in the Mater Hospital.
The married father of one received a number of injuries to his head and neck when he was set upon close to the Royal Canal.
Three 18-year-olds have been charged in connection with the attack.
A fourth teenager who was questioned about the attack has been released by gardaí. A file is being prepared for the Director of Public Prosecutions.
Detectives at Mountjoy Station are appealing for anyone who witnessed the incident to contact them on 01-6668600.
