Two men have been arrested in connection with the murder of Darren Guerrine in Dublin four years ago.
The 21-year-old was killed on 18 February 2008.
One of the suspects is in his mid 30s, and is being detained at Kilmainham Garda Station.
The other is in his late 20s, and is being held at Kevin Street Garda Station. Both men can be detained for a total of 72 hours.
Mr Guerrine was shot once in the back of the head with a shotgun.
His body was found at the back of the Jamestown Industrial Estate along the Grand Canal by a man on his way to work.