The man shot dead in the Kilteragh housing estate in Dooradoyle today may have been murdered in a case of mistaken identity, it has emerged.
The man was named locally as Shane Geoghegan.
It is believed the 28-year-old, who played rugby for local club Garryowen, was shot dead by a killer who intended to gun down a local drug dealer.
Gardaí said they were trying to establish why the man was shot.
A Garda spokesman said: "There was no apparent reason why he was targeted."
A Garryowen club spokesman said the death of Shane, who captained the third team, was a tragedy.
Local Fine Gael councillor Richard Butler said the community was stunned by the killing.