Murder accused told gardaí he believed life was at risk
By Alison O'Riordan
Murder accused Derek Boyd told gardai that he believed his life was at risk and that he acted in self-defence when he fatally stabbed another man who had let himself back into the defendant's north Dublin home and refused to leave.
The accused man described to officers how he grabbed a kitchen knife and warned the deceased Mark Carroll "not to come any closer". However, he said Mr Carroll "lunged" at him and, during a struggle, tried to take the knife from the accused.
"I believed if he succeeded, he would use it against me," Mr Boyd said in a statement.
Mr Boyd also said that, "given what had happened with his sister", he "did not want to harm anyone intentionally and I certainly did not intend to end someone's life".
It is the prosecution's case that Mr Boyd stabbed Mr Carroll with the intention of killing him or causing him serious harm.
Detective Sergeant Niall Murray on Tuesday agreed with Sean Guerin SC, prosecuting, that efforts were made to establish the whereabouts of Derek Boyd in the aftermath of the events of June 9th, 2024.
Det Sgt Murray said that he became aware from CCTV footage that Mr Boyd had taken a ferry to Scotland about nine hours after the incident.
The detective testified that over a year later, on August 2nd, 2025, he was contacted by a solicitor acting on behalf of Mr Boyd, who said that the accused man wished to present himself to gardai regarding the death of Mr Carroll.
Under cross-examination by Brendan Grehan SC, defending, Det Sgt Murray agreed that Mr Boyd had "effectively turned himself into" gardai.
The next witness, Garda Gary Moore, told Mr Grehan that he had conducted an interview with Mr Boyd on August 5, 2025 at Finglas Garda Station. Gda Moore then proceeded to read Mr Boyd's statement into the record before the jury.
At the outset, Mr Boyd said he was making the statement in response to "the allegation" that he had "unlawfully killed" Mark Carroll on June 9, 2024, which the accused said he denied.
Mr Boyd said he had acted "in self-defence that night" and did not intend to kill or severely harm anyone.
In his statement, the accused man said his "late sister" Sandra Boyd had died on March 19th, 2022, in "a tragic accident" in which he was sentenced to a term of imprisonment of five years, with the final three years suspended.
The accused said he had moved into his late father's home at Scribblestown Place when he was released from prison and that his partner Chantelle, would stay over with him there.
Verbal altercation
"In the weeks before the incident, I was having an issue with a neighbour in the Scribblestown area," Mr Boyd said. Mr Boyd said that on the morning of June 8th, 2024, he had "ran into this individual" and they had "a verbal altercation".
"This individual and what I believe to be his son made threats to me. Owing to my suspended sentence still being active, I knew that I couldn't get into a physical altercation as that could have reactivated my suspended sentence".
"In an effort to deal with matters", Mr Boyd said he contacted a relative and asked him to come to Scribblestown and "sort out the incident" with the person in question.
However, the accused man said his relative contacted Mark Carroll to come down to Scribblestown and "give me a hand".
The accused continued: "Mark was known as a violent person and an enforcer and was well able to handle himself. While I would have known Mark relatively well to see, we wouldn't have been very close at all".
Mr Boyd said Mr Carroll had driven to his home at Scribblestown. "In relation to the text I sent Mark, which said 'Duck that c**t, it's sorted,' that was in reference to me sorting out the issue with the neighbour, and that Mark was no longer required. However, Mark was already on his way to my house at that stage and arrived shortly after me sending that text".
The accused continued: "When Mark and Megan [Rock - the deceased's girlfriend] arrived, we made a plan to go out for a few drinks together as we hadn't seen each other in a while and I appreciated him coming down".
Mr Boyd said the three of them continued drinking at his house at Scribblestown Place along with his girlfriend Chantelle Harcourt.
Mr Boyd recalled "issues" with Megan and Mark's relationship being brought up during the conversation.
"It was brought up that Megan had a barring or restraining order against Mark for being violent towards her .... I can remember the topic of Megan withdrawing the complaint against Mark coming up, and I requested Megan to send a text to Mark's phone confirming she would do that as proof. This was said jokingly. I'm not entirely sure if Megan sent those texts, but if she did they would be on her and Mark's phones".
The accused told gardai that after Chantelle and Megan came back from the shop, he must have said something offensive to Megan as she hit him across the face.
"I did not retaliate against Megan, but Mark and I had a go at each other in the kitchen. The atmosphere became very tense and I asked Mark and Megan to leave my house. They did so, and I believed that would be the end of it.
However, Mr Boyd said Mark was aggressive when he "came back into" his house a few minutes later. "He [Mark] let himself in. I looked down the hall from the kitchen, and I told him to leave again, but he didn't.
"I was standing in the kitchen, and Mark was at the end of the hallway. Chantelle was upstairs. We were aggressively speaking to each other".
"I did not want any confrontation. I told him to stay back. He kept coming towards me. I believed that I was in serious danger, and I had no time to think of any alternative way out. I grabbed the nearest object to me, which happened to be a kitchen knife. I held it in my hand and warned him again not to come any closer.
Mr Boyd said despite his warning, Mark "still came at me".
A struggle
The accused continued: "He lunged at me aggressively at the kitchen door, and we began to wrestle and struggle. During this struggle, he tried to take the knife from me. I believed that if he succeeded, he would use it against me. I genuinely believed my life was at risk. In that moment, I used the knife to protect myself."
Mr Boyd said Mark left his house after the incident. "I knew I had injured him, but I did not realise how serious it was. I ran after him but I did not believe that I had killed him or that I seriously injured him. Given what has happened with my sister, I did not want to harm anyone intentionally, and I certainly did not intend to end someone's life.
"When I realised how serious things were I panicked and ran back into the house. I did not know what to do, and I left the scene and fled the jurisdiction without knowing the seriousness of Mark's condition. My actions were out of fear and confusion. I also believed that my suspended sentence would be reactivated.
"I acted solely to defend myself from what I believed was an immediate and very real threat to my life. I did not seek out violence. I gave verbal warnings and only used force when I had no other choice. I maintain that I acted in lawful self-defence," concluded the accused man.
Mr Boyd (31), with an address at Scribblestown Place, Finglas, Dublin 11 has pleaded not guilty to murdering Mark Carroll (34) at his home on June 9, 2024.
The accused man has also pleaded not guilty that on the same date at the same place, he did without lawful excuse make to Megan Rock a threat to kill her or cause her serious harm, intending her to believe the threat would be carried out.
Mr Boyd has further pleaded not guilty to the charge that on the same occasion he assaulted Ms Rock, causing her harm.
Mr Boyd's partner, Chantelle Harcourt, had previously stood accused of impeding his prosecution by making an effort to clean the scene before gardai arrived.
However, Mr Guerin told the jury on Tuesday that the State would be entering a nolle prosequi against Ms Harcourt on this count, meaning that the State will not be proceeding with the allegation of the act to impede in relation to her cleaning the house at Scribblestown Place.
Mr Guerin told the panel that the second count of Ms Harcourt making a false statement remains.
Ms Harcourt (34), of Primrose Grove, Darndale in Dublin 17 has pleaded not guilty on the same date at Blanchardstown Garda Station, in circumstances where another person had committed an arrestable offence, namely murder, and knowing or believing that person to be guilty of that offence or of some other arrestable offence, did without reasonable excuse an act with intent to impede the apprehension or prosecution of the said person.
The trial continues on Wednesday before Judge Melanie Greally and a jury of seven men and five women.
