John o’regan was shot dead while cycling to work one April morning last year.
The 48-year-old window cleaner was shot up to six times after he was approached by an unknown man who was cycling a push bike and wearing a high-vis jacket.
It happened at Gateway Avenue, Ballymun at around 8:30am on April 15.
Crimestoppers has today launched an appeal for information in relation to the murder.
The offender fled the scene on his bike and travelled across Ballymun Road in the direction of Collins Avenue.
There was very heavy traffic during this period and a number of witnesses saw the offender as he was making his escape from the crime scene.
Detective Inspector Gus Keane said: “We are anxious to speak to anyone who has information in relation to the murder of John O’Regan.
Perhaps you were aware of suspicious activity in the run up to or on Tuesday 15th April last year and thought nothing of it at the time? Even the smallest piece of information, which may seem insignificant, might help with the investigation.
Anybody with information can call Crimestoppers on 1800 25 00 25.
Calls to Crimestoppers are anonymous. Callers do not need to leave their name or address. You may receive a reward for information which significantly the investigation.