A 39-year-old man from Donegal has pleaded not guilty by reason of insanity to the murder of his grandfather at the Central Criminal Court. Derek Mulligan is accused of causing fatal injuries to Derek Burns, aged 78, at Carrickcoyle on 19 December 2023. Two psychiatrists have given evidence that Mulligan was suffering from paranoid schizophrenia at the time and meets the criteria for a special verdict of not guilty by reason of insanity. Defence counsel argued that a just and humane society treats those who are unwell with specialist care rather than punishment, emphasising Mulligan's serious mental health deterioration and childhood trauma. The prosecution acknowledged convergence in psychiatric opinion regarding Mulligan's mental disorder. The jury at the Central Criminal Court is expected to begin deliberations on Friday. Mulligan faces additional charges of property damage, making threats, and assault, to which he has also pleaded not guilty by reason of insanity.
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Original report plus public source leads and related archive reports used for review context.
Public source leads
- 'Just and humane society' seeks not to punish those who are unwell, defence reminds murder trial jury - BreakingNews.ie BreakingNews.ie · Fri, 27 Mar 2026 07:00:00 GMT
- Donegal man who killed grandfather committed to Central Mental Hospital - BreakingNews.ie BreakingNews.ie · Mon, 13 Apr 2026 07:00:00 GMT
- Man found not guilty of murder by reason of insanity - RTE.ie RTE.ie · Fri, 27 Mar 2026 07:00:00 GMT
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