She has been described as a "skilful manipulator of people" who will stop at nothing to get her own way when it comes to her own children.

It has been almost three years since Catherine "Cassie" Watter abducted her twin daughters Isabella and Bronte from their Townsville primary school and forced them into a life on the run, a life underground.

Since that April 4, 2014 morning when they kissed their father goodbye - not knowing it would be the last time they would see him - the girls have probably not seen the inside of a classroom.

The trio is believed to be hiding out somewhere in Queensland but police have admitted that they could "literally be anywhere in Australia".

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More than 100 tip-offs, including sightings in NSW, Victoria and Western Australia, have come to nothing but investigators hope age-progressed images of Isabella and Bronte released today will finally lead them to the girls.

Their father Michael Watter, who has sole custody of their girls by consent, told News.com.au that Cassie is being protected by a network of misguided supporters who may have been told a repulsive web of lies she has spun to justify her actions.

They include fabricating claims that he sexually molested his daughters and raped her daily - allegations found by the family court to have no basis in fact.

Mr Watter has the full support of police, who have issued a warrant for the 43-year-old, who is also known as Catherine Lee Watter and Catherine Doubleday, on charges of child stealing.

Isabella (left) and Bronte Watter, aged 9 years, in a computer generated image released by Queensland Police. Photo / Supplied
Isabella (left) and Bronte Watter, aged 9 years, in a computer generated image released by Queensland Police. Photo / Supplied

In June, Queensland Detective Senior Sergeant David Miles admitted police had been frustrated at every turn by Cassie's network of supporters, whom police suspected of setting up false identities and a series of "covert bank accounts" on her behalf.

"In their defence, the people who are supporting her believe that she took Isabella and Bronte to save them from a life of abuse," a distraught Mr Watter told News.com.au.

"She is a skilful manipulator of people and in their minds they are doing the right thing by the girls but in fact the opposite is true. Cassie has taken Isabella and Bronte away from everything they knew, she has destroyed their whole world.

"(In the lead up to the abduction) they were seeing their mother each week, really enjoying the visits at the contact centre. They were happy girls at school, they loved their teachers and friends. They're not in school now at all, I don't think. We believe they are being homeschooled by their mother, just as she was as a child."

Mr Watter said Cassie agreed to the custody arrangement after she was caught trying to coach her daughters into lying about being molested by their father during interviews with police and family court social workers.

"We've got videos as part of the court process that show Bronte saying to police; 'mummy's so funny, she plays this game where she plays the police and she asks me questions to make it so we can live with her'," he told News.com.au.

"The plan was: she takes the kids and disappears while her family and her supporters continue to lobby police and child safety advocates who they think might be able to advance her cause."

Asked what he would say to his ex-wife's protectors, Mr Watter urged them to contact police and hear the truth for themselves.

"Time and time again these issues have been raised by Cassie and found to be untrue yet she is continuing to lie in order to maintain the support around her and two little girls are paying the price," he said.

"If there are any concerns that people have about me and my children then they should take them to the police and let the authorities deal with it instead of taking upon themselves to deal with it themselves.

"They've had three years to gather the evidence, let the police sort it out."

Mr Watter today made a fresh appeal for public help in finding his daughters and their mother.

New computer-generated images showing how Isabella and Bronte might look today, have been released by police in the hope they will trigger recognition in a member of the public.

"It's exciting to put out these images but it's also very emotional. It's a reminder that it's been nearly three years and I don't know them anymore," he told News.com.au.

"I have kept all their Christmas and birthday presents but when I go shopping for them, I think; 'they're not little kids anymore, they probably don't even like the Wiggles anymore'."

Mr Watter, who has established a website called Find the Twins to generate tip offs from the public, said he would never give up searching for his daughters.

Townsville Child Protection Investigating Unit detective Senior Constable Kate Ringberg said police needed the public's help to track them down.

"Someone may have seen Isabella and Bronte and not even realised it was them," she said.

"With these updated photographs ... it will help to remind people that they are still missing and police are still looking for them.

"They could be living next door, they could be going to the same school as your children, they could be in the camp next to yours, they could be sitting next to you right now as your read this.

"Police are requesting that members of the public use their social media accounts to share the new photos of Isabella and Bronte."

At the time of the twins' disappearance Bronte was described as being approximately 100cm tall with a slight build, fair skin and long light brown hair.

Isabella was described as being approximately 100cm tall, of slight build, with fair skin and short light brown hair.

Catherine is approximately 163cm tall, with short hair and hazel eyes.

Warrants to return the children to their father's custody have been issued by the Family Law Court.