A New Zealand father says he will never forgive Alexander McCartney for abusing his two young daughters.

Bob, who only wanted to be referred to by his first name, said his family had been left devastated by the online abuse.

The father said his eldest daughter was just 12 when she was contacted from the other side of the world by McCartney in December 2017.

At Belfast Crown Court, McCartney, from Newry, Northern Ireland, was jailed for life with a minimum of 20 years for his crimes.

The court heard how he forced the girl to send him intimate pictures and then used them to blackmail her into sending images of her younger sister, who was 10.

Bob told the PA news agency: “She friended my eldest daughter on Snapchat, it was just a random connection.

“Then, within a few months, he built trust with her, she thought she was talking to a woman, not a man.

“As part of that trust, that friendship that developed, he then got her to pose for a nude photo, which she sent.

“Once he had that, he had the power and it was a case of playing by his rules.

“He manipulated and blackmailed her into sending more pictures which included my younger daughter, photos of her ended up being sent as well.”

The father said his younger daughter was oblivious to the abuse.

He said: “She thought they were two sisters dressing up and doing silly things together in the supposed safety of their bedroom.”

Bob said McCartney then used his eldest daughter’s Snapchat contacts to contact her cousin, who was 17 at the time.

He said: “She tried to blackmail her cousin to get my daughter to send more photos.

“Luckily, she was mature enough and smart enough to realize it wasn’t right.

“She went to my wife’s house with him and we went straight to the police with him and he got out of there very quickly.”

Bob said that within a few months, McCartney was being followed and they became aware that he was part of an investigation that spread around the world.

He said his eldest daughter, now 18, is still dealing with the trauma of her experience.

“It had a severe impact. He has a lot of anxiety, takes anti-depressant medication.

“Even at her age, she still had no semblance of a boyfriend or girlfriend.

“She really seems to have issues with trust, with building relationships with people.

“That’s the hardest part for us, most of her friends have partners.

“When I go out, I go out together. It often lags behind.

“This is the part we see every day. I think the scarier part is how she deals with it behind closed doors.

“It’s hard, you don’t want to constantly bring it up, reliving it.

“It’s been seven years, but it’s something that will never go away.”

Bob said he wanted to speak out to raise awareness for other parents about online dangers for children.

He said: “As a parent, you can be vigilant, but you can only do so much.

“Once the kids come home from school, they’re online, talking to their friends. You can’t take all that away, it’s part of the world I live in.

“For us it’s about being vigilant and having that communication with your kids so they know they can reach out and say this doesn’t feel right.

“These children are innocent; they don’t understand blackmail, they don’t understand manipulation, they can’t understand why anyone would do this to them.

“It’s about getting parents to talk to their kids about online safety.

“Do you 100% know who I’m talking to?”

He added: “Having both daughters involved is excruciating, as a parent it’s devastating.

“Within the four walls of your home, they should be safe.

“He manipulated and preyed on their innocence for his own sick pleasure.

“We will never forgive and we will never forget the horrible things this predator has done.”