A court has heard that a 12-year-old girl took her own life rather than comply with an online abuser’s demands.

Alexander McCartney, 26, of Lissummon Road outside Newry, pleaded guilty to manslaughter earlier this year after the girl killed herself.

McCartney has previously admitted 185 charges, including 70 child victims.

He is being sentenced for a litany of crimes in what has been described as “the UK’s largest catfishing case”.

Throughout the hearing on Thursday, McCartney sat in the dock looking downwards at his feet, with his hands covering his ears.

But the court could hear every word of the heart-breaking detail of his campaign of abuse.

Catfishing involves the use of a false identity online to befriend and exploit victims.

In this case, it involved the severe sexual exploitation of young girls aged 10 to 16 on social media, mostly Snapchat.

Pretending to be a girl, McCartney found and befriended girls who were said to be struggling with sexuality all over the world.

He used flattery to get a compromising photograph and then use it to blackmail and threaten the children into committing appalling acts or he would publish the images online.

McCartney told one girl that he would get people to come to her house to rape her if she didn’t comply.

The prosecution said that McCartney first came to the police’s attention in 2016 when he was a teenager.

Over the next three years searches were conducted and devices seized on four occasions.

As these devices were studied, the severity of McCartney’s offending was laid bare.

McCartney pled guilty to the 185 charges in four tranches in 2021, 2022, 2023 and 2024.

The prosecution lawyer said “the harm he has caused is unquantifiable”, adding that “he degraded and humiliated [the victims]”.

Throughout the hearing, the court heard of the depravity of McCartney’s actions, children pleading for their torment to stop as he demanded they commit acts of humiliation, abuse and danger.

Prosecutors said he did this for his own sexual gratification.

In a victim impact statement, the family of the 12-year-old girl who took her own life said: “Our lives will never be the same again.

“We didn’t get to see her graduate, walk down the aisle or have children. We have been robbed and lives have been changed forever.”

The court heard that McCartney had claimed that he had been the victim of catfishing in his teens, but prosecutors said there was no evidence to support that claim.

During the hearing, some of McCartney’s messages to the children were read to the court.

Others were provided to the judge in a pack, which he said he read with “great difficulty”.

“It’s excruciating really,” he said.

“We’re into new territory here really.”

In mitigation, the defence lawyer said it was “not hyperbole to describe this case as quite horrific” but he added that McCartney offered genuine remorse.

He said that the fact that McCartney said that he himself had been catfished was not an excuse but that it had “shaped his behaviour”.

The judge said some of the offences can carry a life sentence.

He hopes to pass sentence next week.

The hearing will take place in the afternoon to facilitate many of McCartney’s overseas victims.