An online predator who drove one of his catfish victims in the US to take her own life has been jailed for at least 20 years.

Alexander McCartney, 26, who admitted 185 charges involving 70 children, was given a life sentence with a minimum term by Mr Justice O’Hara at Belfast Crown Court on Friday.

McCartney, who posed as a teenage girl to befriend young females on Snapchat before blackmailing them, lured in victims across the world.

McCartney is one of the world’s most prolific online offenders. While he was jailed for the charges relating to 70 victims, it is believed that the number of children he abused is about 3,500.

Mr Justice O’Hara told the court that the five years McCartney had already spent in custody would serve as part of his sentence.

He said: “The result is that he will be eligible for consideration for release by the parole commissioners, but not until 2039.

“I do not envy the commissioners having to reach their decision at that point.”

McCartney sat in the dock of the court with his head bowed for most of the sentence.

Twelve-year-old Cimarron Thomas, from West Virginia in the US, took her own life in May 2018 rather than comply with McCartney’s demands for her to involve her younger sister in sex acts.

Eighteen months later, her heartbroken father, Ben Thomas, also died by suicide.

McCartney previously pleaded guilty to manslaughter relating to Cimarron’s death.

Cimarron Thomas
Cimarron Thomas took her own life in May 2018 while being blackmailed by McCartney (Family handout/PA)

He also admitted almost 60 counts of blackmail, dozens of charges related to making and distributing indecent photographs and scores of charges of inciting children to engage in sexual activity.

Victims were identified all over the world, including Australia, New Zealand and the US.

McCartney, originally from Lissummon Road outside Newry, Northern Ireland, used his technical knowledge as a computer science student to carry out his crimes.

His offending was carried out from the bedroom of his childhood home.

Mr Justice O’Hara said McCartney had caused harm to young girls across the world.

He said: “The prosecution has described the harm caused by the defendant as unquantifiable.

“I accept that description, subject to the proviso that the harm is inevitably and indisputably huge.

“There were young girls, with younger siblings, all over the world, whose childhoods have been scarred by this defendant.

“In many cases that fact may not be known to their adult carers.”

The judge said he did not accept McCartney’s claim that he had started offending after becoming a victim of catfishing himself as a young teenager.

He said: “In my judgment the evidence points significantly but not necessarily conclusively in the direction of something not having happened to him.

“It is, therefore, my conclusion that the defendant has not proved on the balance of probabilities that he himself was the victim of catfishing when he was 14 or 15.

“Even if I am wrong in that, however, I find that in the circumstances of this case any mitigation would be minimal.

“The fact is that even in his own case, the sadism that he showed to others far exceeds any specific or identified abuse alleged to have been inflicted on him.

“Lest it be forgotten, he kept offending in an even more sinister, dramatic and appalling manner even after his first arrest, and his second arrest, and his third arrest.”

The judge said he was unaware of any case where an offender had used social media on such an “industrial scale to inflict such terrible and catastrophic damage on young girls”.

Road sign for Lissummon Road outside Newry
Road sign for Lissummon Road outside Newry, Northern Ireland, where Alexander McCartney was originally from (Brian Lawless/PA)

He added: “The defendant was remorseless. He ignored multiple opportunities to stop. He ignored multiple pleas for mercy. He lied and lied and then lied again.”

The judge added: “In my judgment it is truly difficult to think of a sexual deviant who poses a greater risk than this defendant.”

Catherine Kierans, from the NI Public Prosecution Service, said some of McCartney’s victims have never been identified, despite exhaustive efforts by investigators.

“McCartney’s crimes have harmed thousands of children and left them and their families dealing with the traumatic aftermath,” she said.

“Their courage stands in stark contrast to his cowardice in targeting vulnerable young girls.

“I want to recognise their bravery, which has been an inspiration to everyone who worked on this case.

“The police and prosecution teams, including the senior independent barristers who assisted with this case, were dedicated to working together to end the harm McCartney was causing.”

Detective Chief Superintendent Eamonn Corrigan, of PSNI, said police had been determined to bring McCartney to justice.

He said: “McCartney is nothing but a disgusting child predator who was posing as young girls online to groom, manipulate and sexually abuse his victims, as young as four, to satisfy his own sexual perversions and that of other online child sexual offenders.

“We have worked tirelessly around the clock on this case, with international criminal justice partners to safeguard victims and build a robust case against this man whose offending has shocked communities around the world.”

Stormont Justice Minister Naomi Long paid tribute to the work of the PSNI and PPS, adding that her thoughts are with the victims of McCartney.

“The level of depravity, deviousness and utter disregard Alexander McCartney demonstrated for his young victims was horrifying, and those victims, not all of whom will ever be able to be identified, deserved justice to be done,” she said.

“McCartney committed his vile crimes behind a cloak of online anonymity, but through a comprehensive and robust operation across the criminal justice system he has been exposed as the vile and prolific child sexual predator that he truly is.

“I hope that today’s sentencing will also serve as a deterrent and a reminder to other predators that online abuse is not beyond the reach of the law.

“However, above all else, today my thoughts are with the family and friends of Cimarron Thomas. She, and McCartney’s other victims, deserved never to be exposed to his depravity, cruelty and abuse. Nothing can heal the wounds he has inflicted on his victims and their families, but I hope that seeing him held to account for his actions brings some small comfort to them.”