A woman who was abused as a teenager by one of the world’s most prolific catfish abusers has described her anger that he used her photograph to lure other victims.

Alexander McCartney, from Newry in Northern Ireland, who drove one of his victims in the US to take her own life, was jailed for at least 20 years at a Belfast court last month.

McCartney, 26, who admitted 185 charges involving 70 children, posed as a teenage girl to befriend young females from across the globe on Snapchat and other platforms before blackmailing them.

Cimarron Thomas, 12, 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.

McCartney is believed to be 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.

A new BBC programme has heard from three of McCartney’s victims.

Being catfished – it’s such like a light term for this situation. To me, being catfished – you are on a Tinder profile and your pictures look different to what you look like in real life – that is not this. It is a sex crime and it is horrible

Speaking anonymously, they have described the devastating impact of McCartney’s actions.

One of his victims, “Emily”, from Oregon in the US, was 14 when she was abused by McCartney in 2018.

He then created online profiles using images of her to sexually abuse other young girls around the world.

She said it made her angry to know he had used her photo to target other girls.

She also said she hoped speaking out would help her to feel closure, “wrapping up this chapter of my life”.

“I know his name. I’ve learned a lot more about him and how he operated. I know he is behind bars,” she said.

I was just confused and scared. I just felt like it wasn’t going to end. It’s like seven years later. I spoke out and talking about it definitely helps. I like who I am nowadays

“There were some tears and hugs from both my parents, it felt good to have that support from them.”

“Violet”, from Virginia Beach also in the US, was 12 when she was abused by McCartney in 2018.

Her concerns were reported to a police officer based in her school, prompting the involvement of the US Department of Homeland Security.

“Being catfished – it’s such like a light term for this situation,” she said.

“To me, being catfished – you are on a Tinder profile and your pictures look different to what you look like in real life – that is not this. It is a sex crime and it is horrible. People have lost their lives over this. I reported him and he got caught.”

She urged other victims to speak out, adding: “Because you truly never know the magnitude of the situation you are dealing with.”

Why (Cimarron had taken her own life) was the biggest question, why? The investigating people went to the school and talked to everybody and nobody had anything concrete to say. It just wasn’t her to do it. That was the hardest part ...

Meanwhile, “Ivy”, from Hawke’s Bay, New Zealand, was 12 when she was abused by McCartney in late December 2017.

She told the programme: “I was just confused and scared. I just felt like it wasn’t going to end.

“It’s like seven years later. I spoke out and talking about it definitely helps. I like who I am nowadays.”

Cimarron Thomas’s grandparents Peggy and Dale Thomas also spoke in the programme.

They said not understanding why she had taken her life had been the hardest part.

“Why was the biggest question, why? The investigating people went to the school and talked to everybody and nobody had anything concrete to say. It just wasn’t her to do it. That was the hardest part – not understanding why she would,” Ms Thomas said.

She said hearing from the Police Service of Northern Ireland (PSNI) about McCartney’s involvement gave them the answers they had been wanting as to why she took her life.

The young girl’s father Ben took his own life 18 months after his daughter’s death, and did not learn what had happened.

(McCartney) was 20. How did he ever think that was normal? It’s almost as if he is infatuated with ('Emily). This ('Emily') is the girl whose images he would then go on to use to send to all the other victims

Ms Thomas added: “Ben just missed her, he just kind of withdrew, because he couldn’t deal with all of it.

“I can’t say how he would have handled it. I think it would have given him a reason to know why. In his mind I think that would have helped him accept it maybe a little better … we’ll never know that.”

Detective Sergeant Neil McInnes, who led the investigation for the PSNI and uncovered the evidence from McCartney’s devices, described the conversations between McCartney and his victims as “horrible acts of manipulation”.

“He was 20. How did he ever think that was normal? It’s almost as if he is infatuated with her,” he said.

“This (‘Emily’) is the girl whose images he would then go on to use to send to all the other victims.”

The series also looks at multi-agency international investigations and the events which led to McCartney being convicted.

The three-part Teen Predator/Online Killer series will broadcast on BBC One Northern Ireland on November 11, 12 and 13 at 10.40pm and on BBC Three from November 18 at 9pm, and on BBC One on Tuesday November 26 at 11pm.

It is also available on iPlayer.