21-year old Jonathan ODriscoll stabbed his 9-year old twin brothers Thomas and Patrick at their home in Deerpark, Charleville.
He took his own life a short time later in nearby Buttevant.
The deputy State Pathologist Dr Michael Curtis has concluded that the cause of death for both twins was multiple stab wounds and death by hanging for Jonathan
The DPP has indicated that no prosecution will be made in relation to the case.
The jury at today’s inquest found that 21-year-old Jonathan O'Driscoll took his own life.
In the case of twins Patrick and Thomas, the jurors returned open verdicts.
They had been informed by the coroner, Dr Michael Kennedy, that the option of returning verdicts of unlawful killing was not available to them as the evidence presented today was that Jonathan O’Driscoll was not of a sound mind.
The jury also said that the family had done everything in its power to assist Jonathan O’Driscoll before the tragic events of last September.
Afterwards the coroner, Dr Kennedy, spoke of the horror and the awfulness that had been visited on the family and he said that Jonathan O'Driscoll was suffering from a serious psychiatric illness at the time of the deaths.
Helen O'Driscoll, the mother of the three boys, said it had been a tragedy which will never leave her.
