Thursday 29 October 2026Compiled from published reports. Every claim links to its source.

Ireland Crime

Every case followed from the first report to the sentence, or to where the reporting stopped.

Case No. 10695Murder · Co. Donegal · 17 Dec 2023

Man who killed grandfather with cement block found not guilty of murder by reason of insanity

Derek Mulligan, a 39-year-old man, was charged with the murder of his grandfather, Derek Burns, 78, who died on 19 December from injuries sustained outside Mulligan's home in the Donegal Gaeltacht on 17 December 2023. After the McFadden family contacted gardaí, Mulligan was detained under Section 12 of the Mental Health Act. On 1 March 2026 the Central Criminal Court returned majority verdicts finding him not guilty by reason of insanity on the murder charge and related counts, including damage to a car windscreen, and he was committed to the Central Mental Hospital. He is due to return before the court on 31 March.

  1. Reportednot reported
  2. Arrestednot reported
  3. Chargednot reported
  4. In courtnot reported
  5. Acquitted1 Mar
  6. Sentenced
reportedhappened, not reportedlatest stagenot yet

Key facts

consolidated from all reports
What happened
  • Derek Mulligan, 39, was found not guilty of murder by reason of insanity by majority verdict.
  • The victim was his grandfather, Derek Burns, 78.
Where
The incident took place outside the accused's home in the Donegal Gaeltacht.
When
  • The incident happened on 17 December 2023, and the grandfather was visited by his daughter at 3.30pm that day.
  • The grandfather died from his injuries on 19 December.
Weapon
The grandfather was beaten with a granite stone and a cement block.
Cause
Two psychiatrists gave evidence that the accused was suffering from paranoid schizophrenia, and the jury accepted this evidence.
Investigation
After the McFadden family contacted gardaí, the accused was detained under Section 12 of the Mental Health Act.
Other details
  • The accused admitted carrying out the assault on his grandfather in garda interviews.
  • The sources do not confirm the nationality of either Derek Burns or Derek Mulligan.
Charges
The accused was also found not guilty by reason of insanity of damaging a car windscreen belonging to Catherine McDermott.
In court
  • On 1 March 2026 the jury returned majority verdicts of not guilty by reason of insanity on all five counts.
  • The accused is due to return before the court on 31 March.
Sentence
The judge ordered the accused committed to the Central Mental Hospital.
12 statements extracted from the articles
  • whatMr Mulligan was found not guilty of murder by reason of insanity by majority verdict. (thejournal.ie)
  • whereThe killing happened outside the accused's home in the Donegal Gaeltacht. (thejournal.ie)
  • whenThe grandfather died from his injuries on 19 December. (thejournal.ie)
  • whenThe grandfather was visited by his daughter at 3.30pm on 17 December. (thejournal.ie)
  • causeThe jury accepted evidence that the accused was suffering from paranoid schizophrenia. (thejournal.ie)
  • weaponThe grandfather was beaten with a granite stone and a cement block. (thejournal.ie)
  • investigationThe accused was detained under Section 12 of the Mental Health Act after the McFaddens contacted gardaí. (thejournal.ie)
  • chargeThe accused was also found not guilty by reason of insanity of damaging a car windscreen belonging to Catherine McDermott. (thejournal.ie)
  • courtThe jury returned majority verdicts on all five counts of not guilty by reason of insanity. (thejournal.ie)
  • courtThe judge ordered the accused committed to the Central Mental Hospital. (thejournal.ie)
  • courtThe accused is due to return before the court on 31 March. (thejournal.ie)
  • otherThe accused admitted carrying out the assault on his grandfather in garda interviews. (thejournal.ie)

The reporting

newest first
  1. 1 Mar2026
    Acquittedthejournal.ie, first report
    Man who used cement block to beat grandfather to death found not guilty of murder by reason of insanity

    Reports the Central Criminal Court verdict of not guilty by reason of insanity on the murder charge and on related charges, the committal to the Central Mental Hospital, and the return date of 31 March.

    victim, Derek Burns, 78, male, non-irish (judged from name)Derek Burnsaccused, Derek Mulligan, 39, male, named, irish (judged from name)Derek Mulliganvictim, Catherine McDermott, female, irish (judged from name)Catherine McDermottvictim, Breege McFadden, female, irish (judged from name)Breege McFaddenvictim, Derek McFadden, irish (judged from name)Derek McFadden