Catfish killer brought down by a phone call

It was a phone call from a 13-year-old girl in Scotland in 2019 that eventually led to the capture of a social media predator described as one of the world’s most prolific child sex abusers.

Alexander McCartney from Northern Ireland claimed he posed as a teenage girl to befriend, then abuse and blackmail children around the world, often sharing images with other pedophiles.

Some of the children were as young as four. Some had never told anyone what they had been through – until the police knocked on their door.

McCartney gradually admitted 185 charges including manslaughter after a 12-year-old girl he abused took her own life.

He has been imprisoned for a minimum of 20 years.

Following contact from Police Scotland, an urgent investigation by the Police Service of Northern Ireland (PSNI) started in March 2019.

Detectives identified Alexander McCartney’s home address, arrested and interviewed him.

64 of McCartney’s devices were seized from his home in the rural Lissummon Road area outside Newry in four separate raids.

These devices contained hundreds of thousands of indecent images and videos of underage girls performing sexual acts while being blackmailed.

McCartney created and used many fake accounts on online platforms, primarily Snapchat, to capture and manipulate them.

PSNI Det Ch Supt Eamonn Corrigan said McCartney had been “offensive on an industrial scale”.

He tricked victims into believing they were talking online with a girl their own age before encouraging them to send indecent images or engage in sexual activity via webcam or a mobile phone.

McCartney used the same pattern each time, the detective said, adding: “He threatened to share these images online for the enjoyment of other pedophiles and use them to further abuse and harass the already terrified and exploited children.”

In one incident, it took McCartney just nine minutes to groom, abuse and blackmail a girl aged just 12.

As time went on, it became clear that McCartney’s depravity spanned not just Britain, but the world. The abuse included the involvement of other people, family pets and objects.

The PSNI worked with colleagues in the US Department of Homeland Security, the Public Prosecution Service and the National Crime Agency, and the victims were located in America, New Zealand and at least 28 other countries.

Many of these children were only identified through the evidence detectives on McCartney’s units.

According to police, he “built a pedophile business” and had “stolen childhoods” from his victims.

In the spring of 2019, the police called Catherine Kierans, acting head of the prosecutor’s office’s serious crime unit.

They said something “big was unfolding…it involved catfish”.

Catfishing is where a person creates a false identity to gain people’s trust and take advantage of them.

Ms Kierans said little girls “average age 10-12 [were] is being threatened in the most depraved way.”

She said some of the children who had been exploited had previously opened up about their abuse, others had remained silent.

“Some of the children had raised the alarm, which helped the police identify him in the first place.

“But some of the kids, until the police knocked on the door, they had never told anyone what they had been through.”

According to Ms Kierans, McCartney insulted “around the clock”.

As the investigation spread across the globe, Ms Kierans said prosecutors realized McCartney had been “very persistent in hiding the images”.

“He would also save the map on Snapchat of where the child was in some cases and that then enabled the police to locate the children.”

His arrest in 2021 was delayed when police discovered the suicide of a little girl in West Virginia, USA.

“From the beginning, the level of abuse was so horrific that we were afraid that once these children were identified, would they be OK?” said Mrs. Kierans.

“Unfortunately, our worst fears were realized when we discovered a little way in that one of the little girls had taken her own life.

“By working closely with the US authorities, we were able to prove that this child took her own life during the abuse while she was still online with McCartney.

“At that point the child’s death was so inextricably linked to the abuse that we felt we had a strong case to say he killed her.”

The little girl was 12-year-old Cimarron Thomas, who in 2018 shot herself while McCartney was abusing her.

McCartney was charged with his manslaughter.

Ms Kierans said it is believed to be the first time an abuser anywhere in the world has been held responsible for manslaughter where the victim and perpetrator have never met in person.

The case was so big that the prosecutors had to be careful with the charges.

“We couldn’t put 3,000 charges on the charge,” Ms Kierans said.

“In the end, there were about 200 charges [relating to around 70 victims] which is probably one of the biggest charges we’ve seen in Northern Ireland.”

McCartney grew up five miles outside Newry and just off the main road to Armagh city.

It’s about as rural as it gets. Farms, a church and a few businesses.

When he first appeared at Newry Magistrate’s Court in July 2019, he was just 21, with long, unkempt hair and the wide eyes of someone surprised to be sitting where he was.

He has spent more than five years in custody at Maghaberry Prison – only to appear in court and be questioned further by police.

In those hearings, he said little other than confirming his name and date of birth and gradually entering a mildly guilty plea.

McCartney attended Newry High School and was into games.

A source told BBC News NI: “He was introverted and socially awkward. He didn’t interact much with people outside his group of friends.

“He might have been on the edge of things, but he had friends who obviously didn’t know anything about this.”

He then took a course at Southern Regional College in Newry, where he was described as “quiet and didn’t really mix with the rest of the class”.

When he was eventually charged in 2019, he was a computer science student at Ulster University.

For those who live in and around his home, the case has been harrowing.

“The whole place was stunned,” said one resident.

“It was whispers at first, then disbelief. I’m sure people talk about it in their own homes, but it’s not discussed in public because people don’t know what to say.”

Another said: “He seemed like a pleasant, amiable, intelligent young man.

“There is nothing extraordinary about him.”

But the extraordinary thing is the extent of his insult; many of his victims had pleaded for the abuse to stop, but prosecutors said he “coldly continued, at times forcing the victims to involve younger children, some as young as four”.

According to Catherine Kierans, McCartney’s depravity was such that it was “one of the most disturbing and prolific cases of child sexual abuse we have ever seen in PPS”.

Ms Kierans said some of the victims have still never been identified despite exhaustive police efforts.

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

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

Additional information and support for those affected by this story can visit BBC Action Line.