GARDAI investigating the murder of Conor Quinn are watching airports and ports in case the suspect in his murder tries to leave the country.
Investigators are also probing whether the killer believed he was acting in self-defence when he stabbed the 24-year-old, leaving him with fatal injuries.
Searches were being carried out in the river and on the river bank for the weapon used in the attack.
The dead man had been recently living in Killavullen and had relatives living in Cork. He had lived in Loughrea in Galway and Kilshane, outside Tipperary town, when growing up. He went to school in Tipperary town.
Mr Quinn's body was identified by his parents in CUH yesterday.
Heartbroken friends have paid tribute to him on Facebook, with one writing: "Still in shock over the tragic news. Can't believe you were taken away like that. Rest in peace cuz. You will always be remembered and never forgotten."
His sister travelled home from India yesterday to be told about his murder. It is understood she was not told of his death until she arrived in Ireland.
Mr Quinn got out of a car in the Bridge Street area of Mallow at around 8.30pm on Thursday night. During a brief confrontation, he was stabbed at least once, before the young man who stabbed him fled the scene.
The killing is thought to be linked to an earlier incident at Cahirmee horse fair in Buttevant, which takes place every July 12.
Gardai have issued an appeal to the killer to turn himself in. He is from the Mallow area. The dead man and the suspect were known to each other.
In a statement, gardaí said: "Gardaí are aware of the background circumstances which precipitated to the engagement and we can assure that any person that comes forward will be dealt with professionally in accordance with the law."
The murder is the fourth in Cork in recent weeks.
Any witnesses are asked to contact Mallow Garda Station on 022 31450, The Garda Confidential Telephone Line on 1800 666 111 or any Garda Station.