The judge said Mr Power was behaving in a very violent and threatening way. He assaulted Kerrie and the court was told he had also assaulted Kerrie's mother.

Kerrie said he grabbed a kitchen knife, which he said was in a bedroom, to defend himself and his mother, although the judge said he did not accept he had been told the full truth about where the knife came from.

Mr Justice McDermott said he did accept Kerrie, who was younger and of slight build, had made decisions under a degree of pressure in a very short time frame in the context of the unexpected attack on his house by Mr Power, who was a tall, well built young man.

He said he also had to take into account that Kerrie was only 17 years old at the time and that his regret and remorse were genuine. He said this was evident from the immediate aftermath of the stabbing. Kerrie called gardaí who came to the house and found him sobbing in the kitchen.

The judge said he had received a number of reports in relation to Kerrie, including a probation report that assessed him as being at moderate risk of violent offending in the future if the risk factors for this were not addressed in a meaningful way. He said according to the report, Kerrie was still not capable of identifying what alternative course of action he could have taken.

In victim impact statements to the court last week, Mr Power's parents said their loss was immeasurable.

His mother Loretta Power said her son did not have a voice in the courtroom and his father Richard said the family had been mentally and physically left without direction. He said their son had been the young blood needed to continue the family fishing business.

Mr Justice McDermott said it often happened in criminal trials that the life, loves, skills and character of the victim of crime, did not appear to be the central concern.

He said trials focused on certain elements of a case, as well as legal rules, and these provided cold comfort for grieving relatives.

Mr Justice McDermott said the damage done to the family was horrendous beyond words. Mr Power had been an exceptionally hard working young man, fuelled by his love for the sea and his father's encouragement.

The judge said his loss was incalculable and nothing he would do or say could alleviate their suffering.

The judge sentenced Kerrie to four-and-a-half years in jail, but suspended the last 12 months for a two-year period, on a number of conditions, including a commitment to engage with therapeutic and addiction services.