Derek Mulligan (39) had pleaded not guilty by reason of insanity to the murder of his grandfather, Derek Burns (78), at Carrickcoyle on December 19th, 2023.

Derek Mulligan (39), with an address at Carrickcoyle, Derrybeg, Gweedore in Co Donegal, has pleaded not guilty by reason of insanity to the murder of his grandfather Derek Burns (78) at Carrickcoyle on December 19th, 2023.

A prosecuting barrister told the trial of Derek Mulligan on Monday that the accused was the victim of serious sexual abuse at the hands of a school caretaker when he was a child and has suffered with a litany of mental health difficulties since his teenage years.