Published Tuesday, 29 April 2014
Father-of-four Aloysius Hackett, 60, was shot twice in the head outside his home near Augher on 4 January, 2013.
The court heard how both he had his father shared a love of Gaelic football.
Sean Hackett played for the Tyrone minors and it was as his father returned home from a GAA meeting that the teenager shot him.
He had always admitted shooting his father, who was nicknamed Wishie, and was charged with murder.
But defence lawyers successfully argued that he had been mentally ill at the time of the killing.
During his trial, the jury heard how despite an excellent well rounded upbringing, the teenager had tried to strangle his mother in the garage of home in October 2012, three months before fatally shooting his father.
His lawyers claimed that he believed that killing one of his parents would place them in heaven to watch over him.
Sean Hackett had planned to kill his mother twice on the day that he shot his father, but the court heard he couldn't bring himself to do it.
In what was described as one of the most extraordinary and complex cases to come before the courts, Sean Hackett was last month convicted of manslaughter on the grounds of diminished responsibility.
On Tuesday afternoon, he was told that he would serve a minimum 10 year prison sentence with a concurrent life sentence and a minimum term of four years for possessing the firearm and ammunition with intent.
Mr Justice Stephens said that the exact diagnosis of his mental state was unclear, but he was at risk of developing schizophrenia.
The judge said he had carefully planned the killing and even practised using the rifle.
He told the court that Sean Hackett had recounted to a doctor how he had felt nervous before shooting his father twice in the head, but after the first shot he felt powerful, excited and wasn't going to stop until he had killed him.
His mother, two brothers and sister, who have always stood by him, wept and held each other in the public gallery as he was then led to the cells.
© UTV News