Speaking earlier, Ms Kierans described the McCartney case as one of the most "depraved, depressing and prolific cases of child sexual abuse that we have ever seen".

Image source, Facebook

McCartney first came to the police’s attention when he was a teenager due to his online activity.

It was a phone call from a 13-year-old girl in Scotland in 2019 that eventually led to his capture.

During an unsuccessful bail application earlier in the case, the court heard that McCartney said he would upload an image of the girl from Scotland to the internet if she did not do what he asked.

Over the next three years searches were conducted and devices seized on four occasions.

As these devices were studied, the severity of McCartney’s offending was laid bare.

The investigation spread across the globe to countries such as Australia, New Zealand and the United States as well as the UK and Republic of Ireland.

Earlier, Mr Justice O'Hara said the details of McCartney's offending put the case “on a par with murder” .

He added that he did not envy the parole board who would have to assess whether McCartney would be eligible for release - which will not be until at least 2039.

BBC Radio Ulster's Evening Extra programme will be covering this story extensively including an interview with a dad of two young girls who were targeted by McCartney.

The programme will also hear from the prosecutor who oversaw the case against McCartney as she talks about how her team put together the extensive case against the killer, while tracking down his young victims across the globe.

We also expect to hear from an online safety expert will give advice on how best children and young people can protect themselves against predators like McCartney on platforms like Snapchat.

You can listen live at the top of this page.

The statement from Cimarron Thomas's grandparents, Peggy and Dale Thomas, was read outside the court.

“We all have been devastated by our granddaughter’s passing," the said.

"We know that nothing that we do or say will bring her back.

"But if we can help another family to not have to go through what we did, something good could come out of her death.

"Parents, please keep the doors of communication open concerning the evil of some people online.”

Peggy and Dale have also taken part in a BBC3 documentary which will be broadcast in the next few weeks.

Read more on this story: Online killer McCartney 'robbed us of granddaughter'

The Police Service of Northern Ireland has released examples of conversations McCartney had with the children he abused.

Once McCartney had received the images from children, he blackmailed them saying he would upload them for "everyone to see".

Cimarron Thomas said she would call the police. McCartney told her he did not care. She said she would shoot herself. He said she had 30 seconds to comply with his demand.

Three minutes later, Cimarron was found by her nine-year-old sister who entered the room after she thought she heard a balloon pop.

She had shot herself in the head with the family's legally-held firearm.

Police have released the 911 call made to an emergency dispatch centre, minutes after the shooting.

The voice of the people who made the call have been redacted.

Earlier, we heard from Catherine Kierans, acting head of the PPS Serious Crime Unit, during the police press conference.

Ms Kierans said today was about McCartney's victims.

"Their courage stands in stark contrast to McCartney's cowardice in targeting young girls," she said.

Ms Kierans added that the victims' bravery had been "an inspiration" to everyone working on the case.

She said McCartney's conviction sends a message to other abusers that their actions have "dire consequences" and there is "nowhere to hide".

Ms Kierans said her most important message was to children and young people.

She told them if someone demands sexual images or videos it is a crime.

"You are not to blame in any way," she said, urging them to talk to a trusted adult.

Image source, Getty Images

Earlier, we heard from Det Ch Supt Eamonn Corrigan, who thanked "other police services around the world" who worked with the PSNI on the McCartney case.

The Police Service of Northern Ireland has provided a statement on behalf of the US Department of Homeland Security.

Special Agent in Charge Derek W Gordon said that “Alexander McCartney committed some horrific and disturbing crimes and deserves every minute he serves in prison”.

“His wretched conduct tragically led to a child in West Virginia taking her own life. We are thankful that our law enforcement partners in Northern Ireland saw fit to apprehend and charge McCartney for his role in the girl’s death.

“Their investigation and prosecution of this case were nothing short of brilliant.”

Image source, Reuters

Police believe McCartney had up to 3,500 victims, he groomed the majority of them on Snapchat.

In a statement a spokesperson for the social media app said: “The sexual exploitation of any person is horrific and illegal and our hearts go out to the victims in this case.

"If we discover this activity, or it is reported to us, we remove it, lock the violating account and report it to the authorities.

"We have extra protections for teens to make it difficult for them to be contacted by strangers and we have expanded in-app notifications to ensure teens are in touch with people they trust.

"Through our in-app family centre parents can also see who their teens are talking to, and who their friends are.”

Stay with us for the latest.

McCartney has caused “serious and long-lasting harm on what we estimate to be around 3,500 victims and their families," Det Ch Supt Corrigan says.

“As far as I am concerned there is only one place for McCartney and that is behind bars. I am glad his offending has been uncovered and that it has today been taken seriously by our criminal justice system."

Det Ch Supt Corrigan thanks his counterparts in America and around the world for their help in this investigation.

“It should not be underestimated how difficult this job is, to watch and grade child abuse imagery to bring someone like McCartney to justice and locate and safeguard his victims is no easy feat.

“All of us working on this case have families at home and we wanted to protect these children as if they were our own.”

Corrigan says the devastation McCartney has caused and the lives he has stolen cannot be underestimated.

To young people, he says: "Please come forward if someone is threatening you online."

Det Ch Supt Corrigan adds: “My team and I welcome today’s sentencing. Investigating Detectives have been determined to bring McCartney before the courts to answer for his crimes and today we have done just that.”

He says that McCartney’s crimes were 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," he says.

Det Ch Supt Corrigans says Cimarron pleaded for McCartney to stop and said she would shoot herself, he simply replied “I don’t care”.

He says McCartney then started a countdown for her to comply with his sick requests or he would carry out his threat to send previously captured images to her contacts.

It was during this countdown that the child shot herself.

The detectives says McCartney may as well have pulled the trigger himself.

Her father took his own life in the aftermath of her death, never knowing the truth of what happened, the detective adds.

Corrigan says in May 2018, Cimarron Thomas, a 12-year-old girl from West Virginia took her own life.

She shot herself with a legally held handgun during online contact with McCartney, as he was attempting to coerce her into involving her younger sibling. In March 2024 he pled guilty to a charge of manslaughter.

This makes him the first person in the UK to be sentenced for manslaughter when the victim resided in a foreign jurisdiction, he explains.

Image source, Pacemaker

Police discovered that “on one harrowing occasion” it took McCartney nine minutes to groom, sexually abuse and blackmail a girl of only 12 years of age.

“Many of these children were too afraid to speak to their parents and guardians about the abuse, only identified through the evidence detectives located on McCartney’s devices and the diligence and determination of the officers,” Corrigan explains.

Corrigan says the police were able to establish that McCartney used the same behaviour pattern every time to groom victims into believing they were talking online with a girl of a similar age.

Regularly, taking on the identity of previous girls he had abused, using their illegally obtained images to catfish others.

He would then encourage them to send indecent images of themselves or engage in sexual activity online.

Then threatening to share these images online for the pleasure of other pedophiles and use them to further abuse and harass the already terrified and exploited children.

Det Ch Supt Corrigan says McCartney made and used many fake accounts across various online platforms to entrap and manipulate them.

It became clear to the police that McCartney’s offending spanned not only right across the United Kingdom, but across the world.

Corrigan says they were working with Homeland Security, the Public Prosecution Service and National Crime Agency, victims were located in America, New Zealand and at least 28 other countries.

Image source, Pacemaker

The Police Service of Northern Ireland (PSNI) say they were initially contacted following a report from Police Scotland that a 13-year-old girl had been groomed by an adult suspect believed to be residing in Northern Ireland, using the alias of a 13-year-old girl.

Detectives describe McCartney as a “disgusting child predator”.

Speaking about when McCartney was identified and arrested Det Ch Supt Eamonn Corrigan says: “Sixty-four of McCartney’s devices were seized uncovering tens of thousands of photos and videos of underage girls performing sexual acts whilst being blackmailed.”

Image source, Pacemaker

Catherine Kierans, acting head of the PPS Serious Crime Unit, says McCartney has caused "immeasurable damage".

She says the PPS worked closely with police to build the most effective case to get justice for victims.

You can watch live at the top of this page.