Finn Colclough has been sentenced to ten years in prison for the manslaughter of Seán Nolan in May 2007.
The 18-year-old was found not guilty of murder but guilty of the manslaughter by a jury at the Central Criminal Court in October.
Earlier today, the mother of Sean Nolan has given an emotional victim impact statement at the sentence hearing of her son's killer.
Charlotte Nolan, whose 18-year-old son Seán was stabbed to death in May 2007, said the memory of her son lying dead on a hospital trolley would haunt them forever.
Mrs Nolan also said her family had been deeply traumatised by his death as they face into their second Christmas without him.
She described Mr Nolan as hard-working, loyal and protective of his family.
Mrs Nolan said the family should have been looking forward to organising his 21st birthday party next year, but they were now faced with the task of choosing a headstone, which is something no family should have to do.
Mr Colclough had said he felt threatened by Seán Nolan and two other youths who had stopped outside his home on Waterloo Road to ask for a corkscrew in the eary hours of 26 May 2007.
