The family of a 12-year-old American girl who took her own life while being blackmailed by Alexander McCartney have told of their devastation over her death.

In May 2018, Cimarron Thomas from West Virginia killed herself after refusing McCartney’s demands to involve her younger sister in online sex acts.

Cimarron’s heartbroken father, Ben, died by suicide 18 months later, not knowing what had caused his daughter to take her own life.

McCartney, 26, was sentenced at Belfast Crown Court on Friday after admitting 185 charges involving 70 children.

He pleaded guilty to manslaughter over the death of Cimarron, the first person in the UK to be sentenced for this offence when the victim lived in a foreign jurisdiction.

In a statement, Cimarron’s grandparents said: “We all have been devastated by our granddaughter’s passing.

“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.

Alexander McCartney was sentenced at Belfast Crown Court on Friday (PSNI/PA)

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

McCartney had first contacted Cimarron four days before her death and had blackmailed her into sending images.

She had believed the ordeal was over, but he contacted her again on May 10. The PSNI recovered the online conversation between the two.

Cimarron repeatedly asked McCartney to leave her alone while he coerced her into sending further pictures. At one point she said: “I don’t like this.”

When she told McCartney she would call the police, he responded “IDC” (I don’t care).

Belfast Crown Court heard that a PSNI officer who reviewed the material said Cimarron was “utterly distraught and sobbing at the time”.

McCartney demanded she send pictures of her nine-year-old sister. She responded “Please, not her.”

When Cimarron continued to refuse McCartney’s demands, he began a countdown of 30 seconds before he threatened to post pictures of her online.

He told her: “I am posting, bye. Ben Thomas first (Cimarron’s father). He should see the pix first.”

Cimarron responded: “No, I will obey.”

The conversation then stopped. Three minutes later, Cimarron’s younger sister found her body lying on the floor of her parents’ bedroom.

She picked up her sister’s phone and hit the panic button, triggering a 911 call. Cimarron died later that night in hospital.

A pre-sentence hearing in Belfast was told that Cimarron had told her parents she thought she was bisexual, but the family knew of no reason why she would take her own life.

It was almost three years later that they found out about the blackmail and abuse by McCartney. By then, Ben Thomas had already died by suicide.

A statement read in court from his wife, Stephanie, said that Cimarron’s father felt guilty about his daughter’s death. She added: “He lost interest in life.”

A victim impact statement from Cimarron’s paternal grandfather, Dale Thomas, was submitted to court as part of the sentencing process.

In it, Mr Thomas speaks of the outgoing personality of his granddaughter and their ongoing sense of devastation over her death.

He said “Our lives will never be the same again.

“It has robbed us of many, many years with Cimarron and with Ben and the lives we had planned with them.

“We didn’t get to see Cimarron graduate from school or attend a prom.

“We will never get to see Ben walk her down the aisle on her wedding day or to meet her children.

“We will never get to have the family holidays that we planned just a few days before Cimarron’s death.

“We have been robbed of these memories and our lives have been changed forever.”