A 21-year-old man has been sentenced to six years in prison for the manslaughter of his 17-year-old sister on the grounds of diminished responsibility.
Mr Justice Paul Carney sentenced Patrick O'Dwyer of Shrohill, Ennistymon, Co Clare to six years in prison dating from 30 November 2004.
Mr O'Dwyer is the first person to be convicted of manslaughter on the grounds of diminished responsibility since new legislation governing insanity came into force last year.
In a victim impact statement, Patrick O'Dwyer's mother, Mrs Clare O'Dwyer, said her poor and unfortunate son would have to spend the rest of his life knowing he killed his little sister Marguerite.
She said Mags was a bright intelligent young girl and the grief and sense of loss would never go away.
She said that Patrick and Marguerite had formed a close bond after their older sister, Louise, had left for college and she said the two of them were like peas in a pod.
She said Patrick had had no control over events the night he killed his sister.
