Gardaí in Limerick are continuing to hold an 18-year-old youth in connection with Sunday night's fatal shooting in the Moyross area of the city.
The teenager is being questioned about the murder of 21-year-old Frankie Ryan in the Pineview Gardens estate.
Mr Ryan was sitting in his car on Sunday night when he was shot dead by a gunman who pulled up on a motorcycle.
Gardaí are linking the killing to the ongoing feud between rival criminal gangs in Limerick that has claimed six lives in recent years.