Case No. 0574Murder, assault causing harm, impeding prosecution · Co. Dublin · 9 Jun 2024
Derek Boyd on trial for murder of Mark Carroll in Finglas
Derek Boyd, a man, 31, is on trial at the Central Criminal Court for the murder of Mark Carroll, a man, 34, whom he fatally stabbed with a knife in his kitchen at his home in Finglas, Dublin 11, on 9 June 2024, well after midnight. Boyd fled to the UK and did not return for a year before pleading not guilty to murder and to assaulting Carroll's girlfriend Megan Rock causing her harm on the same occasion, while his partner Chantelle Harcourt, a woman, 34, pleaded not guilty to impeding his prosecution. Boyd was serving a suspended sentence for the manslaughter of his sister Sandra Boyd at the time of the killing. Closing speeches were delivered on 18 July 2026, with the defence arguing self-defence and the prosecution describing the killing as a determined, murderous attack, and the trial continues before Ms Justice Melanie Greally.
- Reportednot reported
- Arrestednot reported
- Chargednot reported
- In court16 Jul
3 reports - Verdict
- Sentenced
reportedhappened, not reportedlatest stagenot yet
Key facts
consolidated from all reports- What happened
- Boyd fatally stabbed Mark Carroll with a knife in his kitchen at his home in Finglas, Dublin 11, on 9 June 2024, well after midnight.
- Where
- The incident occurred at Boyd's home at Scribblestown Place, Finglas, Dublin 11.
- When
- The stabbing occurred on 9 June 2024, well after midnight.
- Weapon
- A knife.
- Cause
- Boyd said he swung the knife at least three times during a struggle after Carroll grabbed him.
- Investigation
- Boyd fled to the UK and did not return to Ireland for a year.
- Charges
- Boyd pleaded not guilty to murdering Mark Carroll and to assaulting Megan Rock causing her harm on the same occasion.
- Chantelle Harcourt pleaded not guilty to impeding the prosecution of Boyd.
- In court
- The trial is before Ms Justice Melanie Greally at the Central Criminal Court with a jury of seven men and five women.
- Closing speeches were delivered on 18 July 2026; the defence argued self-defence and the prosecution described the killing as a determined, murderous attack.
- Other details
- Boyd was serving a suspended sentence for the manslaughter of his sister Sandra Boyd at the time of Carroll's death.
- Carroll had pleaded guilty to assault causing harm to his girlfriend Megan Rock in 2019 and was awaiting trial on a second assault charge at the time of his death.
56 statements extracted from the articles
- whatBoyd fatally stabbed a man who trespassed on his north Dublin home (irishmirror.ie)
- whatBoyd picked up a knife and begged the man he had been drinking with to leave his home (irishmirror.ie)
- whatThe deceased repeatedly threatened to kill Boyd (irishmirror.ie)
- whatMark Carroll grabbed Boyd and during a struggle tried to take the knife (irishmirror.ie)
- whatBoyd broke free and swung the knife at least three times (irishmirror.ie)
- whatBoyd never intended to kill or seriously injure Carroll (irishmirror.ie)
- whatBoyd ran away to the UK and did not return to Ireland for a year (irishmirror.ie)
- whatBoth men had been on friendly terms that day (irishmirror.ie)
- whatMegan Rock is the deceased's girlfriend (irishmirror.ie)
- whatCarroll asked Rock to wait on the street while he returned to the house to sort it out (irishmirror.ie)
- whatBoyd fatally stabbed Carroll with a knife in his kitchen (dublinlive.ie)
- whatBoyd said he swung the knife at least three times (dublinlive.ie)
- whereSandra Boyd died in the kitchen of the family home (irishmirror.ie)
- whereBoyd has an address at Scribblestown Place, Finglas, Dublin 11 (irishmirror.ie)
- whereChantelle Harcourt has an address at Primrose Grove, Darndale, Dublin 17 (irishmirror.ie)
- whereThe incident occurred at Boyd's home in Finglas, Dublin 11 (dublinlive.ie)
- whereHarcourt's address is Primrose Grove, Darndale, Dublin 17 (dublinlive.ie)
- whenThe stabbing occurred on 9 June 2024 (dublinlive.ie)
- whenThe incident happened well after midnight (dublinlive.ie)
- causeSandra Boyd's death was caused by a reckless or negligent discharge of a gun (irishmirror.ie)
- chargeBoyd was convicted of unlawful possession of a semi-automatic pistol and ammunition (irishmirror.ie)
- chargeCarroll pleaded guilty to assault causing harm to Megan Rock at her home in Ashbourne, Co Meath in 2019 (irishmirror.ie)
- chargeCarroll was charged with assault causing harm to a 36-year-old man in 2022 on Phibsborough Road, Dublin 7 (irishmirror.ie)
- chargeChantelle Harcourt stands accused of impeding his prosecution (irishmirror.ie)
- chargeBoyd pleaded not guilty to murdering Mark Carroll at his home on 9 June 2024 (irishmirror.ie)
- chargeBoyd pleaded not guilty to assaulting Megan Rock causing her harm on the same occasion (irishmirror.ie)
- chargeHarcourt pleaded not guilty at Blanchardstown Garda Station to impeding the apprehension or prosecution of Boyd (irishmirror.ie)
- chargeBoyd pleaded not guilty to murdering Mark Carroll (dublinlive.ie)
- chargeBoyd pleaded not guilty to assaulting Megan Rock causing her harm (dublinlive.ie)
- chargeHarcourt pleaded not guilty to impeding the prosecution of Boyd (dublinlive.ie)
- courtBoyd pleaded guilty to manslaughter of Sandra Boyd on 7 October 2022 (irishmirror.ie)
- courtCarroll was awaiting trial on a second unrelated assault causing harm charge at the time of his death (irishmirror.ie)
- courtThe 2022 assault charge came before Dublin Circuit Court in 2024 and was withdrawn after Carroll's death (irishmirror.ie)
- courtDerek Boyd is on trial at the Central Criminal Court charged with the murder of Mark Carroll (irishmirror.ie)
- courtSean Guerin SC was prosecuting (irishmirror.ie)
- courtDefence counsel Brendan Grehan SC suggested the jury acquit Boyd of murder and an assault charge on Rock (irishmirror.ie)
- courtThe trial is before Ms Justice Melanie Greally at the Central Criminal Court (dublinlive.ie)
- courtThe jury consists of seven men and five women (dublinlive.ie)
- sentenceBoyd received a four-year sentence with the final two years suspended for the manslaughter (irishmirror.ie)
- sentenceBoyd received a concurrent five-year sentence with the final three years suspended for the firearm offences (irishmirror.ie)
- sentenceThe two-year suspended sentence was backdated to 21 March 2022 (irishmirror.ie)
- otherBoyd was serving a suspended sentence for the manslaughter of his sister Sandra Boyd at the time of Carroll's death (irishmirror.ie)
- otherSandra Boyd's death was described as an accidental or tragic event (irishmirror.ie)
- otherMark Carroll had come to garda attention over the years dating back to 2006 (irishmirror.ie)
- otherGardai noted Megan Rock was bruised, bloody-faced and visibly shaking when they arrived at her home (irishmirror.ie)
- otherThe male victim in the 2022 charge suffered a double break to the jaw requiring it to be wired shut (irishmirror.ie)
- otherIn the 2022 charge, a male reported getting punched a couple of times to the jaw following a work party (irishmirror.ie)
- otherThe victim and attacker in the 2022 charge knew each other (irishmirror.ie)
- otherCarroll was a member of the defence forces at one point but not at the time of his death (irishmirror.ie)
- otherBoyd said in a statement he believed his life was at risk and acted in self-defence (irishmirror.ie)
- otherBoyd was serving the suspended portion of his sentence for the manslaughter of his sister (irishmirror.ie)
- otherBoyd was serving the suspended portion of his sentence for manslaughter of his sister at the time of the killing (dublinlive.ie)
- otherBoyd fled to the UK and did not return to Ireland for a year (dublinlive.ie)
- otherHarcourt made a statement to gardai at Blanchardstown Garda Station (dublinlive.ie)
- otherThe prosecution described the killing as horrible, pointless and meaningless (dublinlive.ie)
- otherThe defence described the killing as entirely motiveless (dublinlive.ie)
The reporting
newest first- 18 Jul2026Murder accused 'acted out of instinct' when fatally stabbed man who 'trespassed'
Closing speeches delivered at the Central Criminal Court; trial continues before Ms Justice Melanie Greally. Defence argued Boyd acted in self-defence; prosecution described the killing as a 'determined, murderous attack'.
accused, Derek Boyd, 31, male, named, irish (judged from name)Derek Boydvictim, Mark Carroll, 34, male, irish (judged from name)Mark Carrollaccused, Chantelle Harcourt, 34, female, named, irish (judged from name)Chantelle Harcourtvictim, Megan Rock, female, irish (judged from name)Megan Rock - 18 Jul2026Murder accused "acted out of instinct" when fatally stabbed man who "trespassed"
Closing speeches delivered; trial continues on Monday before Ms Justice Melanie Greally and a jury of seven men and five women.
accused, Derek Boyd, 31, male, named, irish (judged from name)Derek Boydvictim, Mark Carroll, 34, male, irish (judged from name)Mark Carrollaccused, Chantelle Harcourt, 34, female, named, irish (judged from name)Chantelle Harcourtvictim, Megan Rock, female, irish (judged from name)Megan Rock - 16 Jul2026Murder accused was serving manslaughter suspended sentence when he killed man
Trial evidence that Boyd was serving a suspended sentence for manslaughter of his sister Sandra Boyd (guilty plea October 2022, four-year sentence with two years suspended, backdated to March 2022) at the time of Carroll's death; details of Carroll's criminal history including a 2019 guilty plea for assault causing harm to Megan Rock in Ashbourne and a 2022 charge for assault causing harm to a 36-year-old man on Phibsborough Road; Boyd's self-defence account of grabbing a kitchen knife; trial before Ms Justice Melanie Greally.
suspect, Derek Boyd, 31, male, named, irish (judged from name)Derek Boydvictim, Mark Carroll, 34, male, irish (judged from name)Mark Carrollvictim, Megan Rock, female, irish (judged from name)Megan Rocksuspect, Chantelle Harcourt, 34, female, named, irish (judged from name)Chantelle Harcourtvictim, Sandra Boyd, female, irish (judged from name)Sandra Boyd