Horrific crimes of ‘catfish’ Alexander McCartney exposed by bravery of 12-year-old girl

The horrific online crimes of Co Armagh ‘catfish’ killer Alexander McCartney would never have been exposed if it wasn’t for the bravery of a 12-year-old girl, according to the detective leading the case.
McCartney (26) of Lissummon Road outside Newry, was last month sentenced to life imprisonment for 185 offences linked to the online sexual abuse of 70 children living as far away as New Zealand and the United States.
In a legal first, he also pleaded guilty to manslaughter after his blackmailing of an American girl, Cimarron Thomas, led to her suicide in 2018.
In a new BBC documentary, Teen Predator/Online Killer, Detective Sergeant Neil McInnes of the Police Service of Northern Ireland (PSNI), said the actions of a Scottish child five years ago were the “catalyst” for what would become an international police investigation.
The girl, who was 12 at the time, alerted her mother about being blackmailed by McCartney after he had duped her into sending a topless image of herself when he pretended to be a teenager named ‘Chloe’ online.
Police reveal in the programme that the child was one of only four of his estimated 3,500 global victims who reported his offending to the authorities.
[ The horrific online crimes of Alexander McCartney, and the questions they raise for the PSNIOpens in new window ]
Three victims detail their harrowing experiences, with one, ‘Emily’, from Oregon in the US, speaking of her “anger” when she learned that he used her online image to sexually abuse other young girls around the world. She was 14 when he first preyed on her.
“I had sent nude photos with my face in them,” she said. “That’s how it started.”
McCartney, a former computer science student at Ulster University, targeted his young victims – many of whom believed they were gay or bisexual – using the social media platform, Snapchat.
He would pose as a girl and trick them into sending intimate photos before revealing they had been “catfished” and threaten to post the images to their friends and family unless they engaged in often extreme sexual acts.
Operating from his childhood bedroom in the family home, McCartney was described by detective McInness a “nerdy, 20 year-old kid in a little rural community”.
What began as a “very standard investigation” after a PSNI officer on an evening shift picked up a complaint from Scottish police about an online conversation “that quickly became sexual” – with the suspect traced to an address in Newry – became a global case involving multiple law enforcement agencies.
“I think it’s important that the whole story is told. If it hadn’t been for the bravery of one young, 12 year-old, we wouldn’t be sat here now,” Detective McInnes said.
A former teenage friend of McCartney’s, Lee, also takes part in the documentary and becomes emotional recalling his shock on learning about his crimes.
“I was super close with Alexander … he’s a monster,” he said.
Lee said McCartney was a fanatical gamer who was always interested in computers and “figuring stuff out”.
McCartney even showed him how to “access the dark web,” something Lee said he had “no interest” in.
The series also hears from the family of Cimarron Thomas, who died by suicide at the age of 12. Peggy and Dale Thomas from Maryland in the US are the grandparents of Cimarron.
They had no idea why their granddaughter Cimarron took her own life in 2018. It was years later when they learned that she had been abused by McCartney including up to the time of her death.
“Why was the biggest question, why? The investigating people went to the school and talked to everybody and nobody had anything concrete to say,” Ms Thomas said.
In 2021 Cimarron’s family were contacted by PSNI and told of McCartney’s involvement.
Cimarron’s father, Ben, died by suicide 18 months after Cimarron’s death. He did not know about his daughter’s abuse or why she took her own life.
“Ben just missed her, he just kind of withdrew, because he couldn’t deal with all of it,” Ms Thomas said.
The full series is available now on BBC iPlayer.