A senior prosecutor has said she had never before encountered a domestic murder with “such a level of premeditation” as that involved in the killing of Natalie McNally.
Catherine Kierans, assistant director in the Public Prosecution Service in charge of the serious crime unit, described the “absolutely chilling” experience of watching YouTuber Stephen McCullagh’s fake livestream gaming session, which he attempted to present as his alibi for the murder.
McCullagh, 36, of Woodland Gardens, Lisburn, denied the charge of murder of his partner, but was found guilty by a jury at Belfast Crown Court earlier this year following a five-week trial. His tariff hearing as part of the sentencing process took place on Wednesday.
Ms McNally, 32, had been 15 weeks’ pregnant with their son when she was murdered at her home in Lurgan in December 2022.
Ms Kierans advised that McCullagh should be charged with murder back in 2023 and put together the prosecution team which presented the case which led to his conviction.
She said: “At the heart of it was the brutal murder of a very young woman who was pregnant, and that is unusual in society.
“I know there’s a lot of talk about domestic violence, but we’re not so immune that a murder doesn’t still shock and horrify everybody.
“So, we’re dealing with a domestic murder, then you’ve got these really unusual features, the level of planning, the premeditation here was off the scale.
“An absolutely calculated murder planned at least for several days in advance, probably longer.
“You’ve then got the framing of an innocent person and saying that they committed the murder, and so it had these unusual features, and probably the one that’s gathered most attention is the fact that McCullagh used a YouTube recording as his alibi in the case, a six-hour video that he claimed he’d been making at the time that this murder was carried out.
“He maintained that lie for several weeks through a lot of police interviews until finally police experts were able to discern that this was not a live video, he had pre-recorded it and played it out on that Sunday, the 18th of December, and once police had cracked that, even McCullagh had to accept then that it was not a live recording.
Natalie McNally was pregnant when she was murdered at her home (Family handout/PA)
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“He still maintained that he had not committed the murder, and that in fact it had been Natalie’s ex-partner.”
Ms Kierans said the case was “unprecedented” in her experience.
She added: “I have been a lawyer for 27 years. I’ve never seen a case like this in terms of domestic murder with such a level of premeditation, planning, thinking of every possible aspect, the wearing of a disguise, the forensic awareness, the framing of the ex-partner.
“The most insidious aspect, which was the ingratiating himself with the bereaved family and spying on them, recording their private conversation, really shocking aspects to this case.”
The prosecutor said that even though the case against McCullagh was circumstantial, she was always confident he would be convicted.
She said: “From the outset, I considered this to be a very strong case.
“In terms of forensic evidence, had McCullagh’s DNA or anything like that been found in Natalie’s home, that wouldn’t be surprising, because he’d been there a lot, so it’s not something that would have really strengthened the case.
“When you consider the strong strands of evidence that we did have, I’m thinking primarily of the CCTV evidence.
“Through meticulous work, police had analysed thousands of hours of CCTV and were able to piece together the journey that the murderer had taken from Dunmurry all the way to Lurgan, then all the way out to Natalie’s home, and then retrace that person all the way back through until they got a taxi to McCullagh’s house.
*******Images to go out after the sentencing*****Catherine Kierans at Belfast Chambers in Belfast. The senior prosecutor has said she had never before encountered a domestic murder with the level of premeditation involved in the killing of Natalie McNally. Picture date: Tuesday April 21, 2026. PA Photo. Photo credit should read: Liam McBurney/PA Wire
“Then we did have footage from nearby McCullagh’s home of him once that taxi had dropped a person off.
“He then came out and disposed of rubbish in a bin he knew was going to be collected the next morning, and also that his phone had activated, having been inactive all afternoon.”
She added: “Then you’ve got the fact that his alibi was demolished, it was an elaborate charade.
“When we talk about a circumstantial case, sometimes people might think that that’s a weaker case, but it’s not at all.
“A circumstantial case can be incredibly strong and it’s all about pulling together lots of strands of evidence.”
Ms Kierans described watching McCullagh’s “violent night” Christmas live gaming stream, which he had falsely claimed to be livestreaming on the night that he killed Ms McNally.
She said: “I found the six-hour video to be absolutely chilling, because we know that it was made as an alibi with this murder in the planning.
“And in that video there are so many references to the date, the times, the distance from Christmas, McCullagh’s plans for the Monday, everything about it suggested that it had been made on the Sunday, the 18th of December, and not several days earlier.
The sentencing hearing took place at Belfast Crown Court (Liam McBurney/PA)
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“So it just makes you think about the level of planning and the level of deception, and the fact that he was able to make that video several days earlier, and then keep up appearances for several days from that point with Natalie, and lie to her, and tell everybody that he was making this video.
“In terms of the content of the video, even calling it the ‘violent night’ Christmas.
“We will never know, because McCullagh has not explained himself, but we have to assume that everything in that video is intentional and deliberate, and so these apparent references to murder, to Natalie, that they are intentional, and that’s really chilling, because you think there’s a level of brazenness, there’s a level of enjoyment, potentially.
“So, it’s really, really sinister.”
Ms Kierans said despite the publicity surrounding the trial “at the heart of it was the brutal murder of a young woman”.
She said: “Natalie was pregnant, she had everything to live for, a very intelligent woman, vibrant, full of life, full of excitement about her little baby coming, and, you know, we never lost sight of that, and we’re just so pleased that we got justice for her family.”
Ms Kierans commended the bravery of McNally’s parents and brothers, who attended every court appearance.
She said: “The dignified and respectful way in which they engaged with the criminal justice system, while also dealing with devastating loss and grief, is remarkable.
“I know this was not easy for them, but their courage and resilience are testimony to them as a family and their love for Natalie.”
