A Northern Ireland man whose online crimes sparked an international “catfishing” investigation involving 70 teenage victims and caused the death of a girl in the US will be sentenced.

Alexander McCartney (26), originally from Lissummon Road outside Newry, admitted 185 charges involving 70 children, but the court was told the real number of victims was much higher.

McCartney pretended to be a teenage girl to befriend other girls on Snapchat before blackmailing her, with victims identified around the world. Catfishing is the term used when someone creates a fake online identity and uses it to deceive and control others.

Cimarron Thomas, a 12-year-old from the US state of West Virginia, committed suicide in May 2018 rather than comply with McCartney’s demands. Eighteen months later, his father also died by suicide.

McCartney pleaded guilty to manslaughter in Cimarron’s death.

He also pleaded guilty to 59 counts of blackmail, dozens of charges of making and distributing indecent photographs, and multiple charges of inciting children to engage in sexual activity.

Mr Justice O’Hara will sentence McCartney at Belfast Crown Court on Friday.

McCartney’s crimes spanned the period from 2014 to 2019, with victims identified all over the world, including Australia, New Zealand and the United States.

As a computer science student, he used his technical knowledge to commit his crimes in the bedroom of his childhood home.

McCartney, who has been detained at Maghaberry Prison since 2019, posed as a teenage girl on the social media platform Snapchat and befriended vulnerable girls aged 10 to 16 who were gay or exploring their sexuality.

Once he had photos of his victims, he would expose his “catfish” and blackmail them into participating in sex acts.

McCartney was arrested several times between 2016 and 2019, but continued to commit crimes despite bail conditions until his arrest.

At a pre-sentence hearing last week, one of the prosecutors said McCartney humiliated his victims and said the damage done to them was “immeasurable.” – P.A.

Alexander McCartney: ‘Catfishing’ harasser will be punished

This week Alexander McCartney, of Newry, Co Armagh, will be sentenced to prison for what has been described as one of the “worst cases of catfishing” to come before the courts in Belfast. Earlier this year, McCartney pleaded guilty to more than 50 racketeering charges and multiple counts of possessing indecent images of children. The former student also pleaded guilty to the manslaughter of a 12-year-old boy he had blackmailed online but had never met. In this episode from March 2024, Bernice Harrison speaks to Irish Time North Correspondent Seanín Graham about the accusations against McCartney and how it happened. global ‘catfishing’ investigation led police to his home in rural Armagh.