She calls him 'big boy', tells him he has a 'sexy' voice and that she can't wait to be reunited with him.

She is 48, he is just 15 years old, and they are mother and son.

Secret police tapes recorded between the pair while police were investigating incest family matriarch, Betty Colt, have for the first time revealed the nature of her relationship with her teenage son, 'Bobby'.

Colt was jailed for 12 months over a plot to kidnap two of her sons from their foster parents.

The 48-year-old was found guilty in September of planning to remove sons Bobby and Billy from care and take them to live on a South Australian fruit-picking farm.

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Betty Colt is put into a police van after being sentenced to a year's jail at Moss vale local Court on Monday

Betty Colt (right) and daughter Raylene arrive at Moss Vale Court on Tuesday

Colt wept and hugged her daughter, Raylene, who had accompanied her to court, when the magistrate read out the sentence at Moss Vale Court, NSW, on Monday.

She was then led out of the court and into a waiting police van to spend her first night in a women's prison in Sydney,

Magistrate Mary Ryan also issued an apprehended violence order, banning her from contacting 14 members of her family, including her 12 children, all of who are thought to have been fathered by immediate relatives.

In the new telephone transcripts, Bobby, who DNA tests indicate is most likely the product of a sexual relationship between Ms Colt and her own father, texts his mother repeatedly during evenings with a flurry of text message hugs and kisses.

She also engages in complex adult conversations with him about the true parenthood of her children, the secret phone records reveal.

Daily Mail Australia can for the first time publish the conversations for the first time following the conviction of Betty Colt.

Betty Colt, pictured in handcuffs being led to a police van and (right) being driven away, is not eligible for parole for at least nine months

Ms Colt, had an unnatural mother-son relationship with Bobby, which Magistrate Mary Ryan described it as 'overbearing, immature and claustrophobic'.

But the phone conversations obtained by listening devices installed in Ms Colt's Samsung mobile indicate an undercurrent of flirtation in her conversations with her son.

Bobby (a court-appointed name to protect the boy's identity) spoke to his mother on a phone smuggled into his foster care bedroom as Ms Colt plotted to snatch him back from family welfare custody.

May 31, 2013, 6.33pm

Betty tells Bobby his voice sounds 'so sexy' on the phone. She says she intends to fight to get him and his brother Billy back out of care and she hopes the 'c****' are listening. She says when she gets him out after he turns 16 he can get his own place if he wants.

He tells her 'the cops' had talked to him about raping a girl at school.

Betty tells him: 'They have nothing'.

She puts on Bobbby's aunt Rhonda, who tells him: 'Your voice got deeper'.

Then Betty tells Bobby again that she likes his voice and '... ohhh, you can say it alright'.

August 8, 2013

9.05pm to 11.09 pm - 15 texts between mother and son.

9.25pm Bobby to Betty: Love you.

9.36pm Bobby to Betty: Love all.

9.56pm Bobby to Betty: Love all.

10.09pm Betty to Bobby: Bobby xoxoxoxoxo.

September 6, 2013

Betty tells Bobby the court case is getting her down, saying: 'I'm meant to have raped you all.

'They reckon I've had sex with you boys even [she names her youngest son and nephew]. Everyone.

Bobby: 'I think we're a bit young for that.'

Betty: 'Sick f****. I'm meant to have put all the girls in a tent and told all you boys who to have sex with. '

Bobby: 'Have they got any proof?'

Betty: 'Well it never happened, so they don't have shit ... they're trying to say that my dad is your dad, not that my dad is your grandad.

'They just want me to get prison time. I've done nothing f****** wrong.'

Bobby: 'All you have done is try to help people. '

Betty: 'That's f****** right. They think I slept with [brother's name] and my dad and they are fathers of my kids.'

Bobby: 'You can have them locked up for making stories.'

September 17, 2013, 6.32pm

Betty: 'How ya been gorgeous.'

Bobby: 'Yeah alright.'

Betty: 'What ya been up to ... you only got a couple of weeks until you're 16, then you can walk out of there.'

Bobby: '...it doesn't feel right leaving when I'm 16, leaving the others behind.'

Betty: '...you pack your bags. We found out DOCS can't intervene if you just walk out. They can't f****** stop yas.'

Two days later, Bobby tells his mother 'they found out who my father is'.

She objects and says ,'no they don't ... your father was Tom Wilson. Don't talk to anyone.'

When two of Betty's daughters appear to have confessed to welfare authorities the true nature of sexual relations in the incest camp, she is contemptuous and unforgiving.

She puts another daughter on to talk about the traitor,Tammy.

Bobby responds, 'She's not one of our family no more ... she's a stupid b****'.

On September 29, 2013

As police are closing in on Ms Colt's kidnap plot as the allotted date draws near for her to be reunited with Bobby, she texts him: 'Love you big boy, love you very very much.'

Four days later Betty Colt was arrested in a car park on the NSW South Coast and charged.

The Colt family was discovered living in squalid conditions on this rural NSW property in 2012.

Many of the children were found to have been fathered by immediate relatives and many had severe deformities

Ms Ryan, who imposed a non-parole period of nine months, said a full pre-sentence report found Colt was unsuitable for any community sentence because she had shown she would not obey any court order regarding ceasing contact with her sons.

'She has absolutely no insight into the damage she has caused them in the past,' Ms Ryan said.

'She denies the abuse or neglect that took place over many years.'

Colt's lawyer Peter Carey said his client would appeal the sentence.

Magistrate Mary Ryan found Ms Colt, 48, guilty of recruiting her son, Bobby, 16, to kidnap his brother, Billy, 15, from foster care, where they were placed after being discovered living at a squalid rural camp two years ago.

The Colt family story of incest, depravity and squalor on a scrub land block just outside an Australian country town in southern New South Wales shocked the world.

Although further charges are expected to be laid against others found on the property, Ms Colt is the first member of the incest family to be successfully prosecuted.

Daily Mail Australia has revealed that police have also successfully taken an apprehended violence order (AVO) against Martha Colt, Betty's sister, who gave birth to five of her own brother's children.

DNA testing has proved that 16-year-old Bobby is the result of a close incestuous relationship between Ms Colt and either her father or a full brother.

Ms Ryan said Ms Colt's attempts to remove her sons from care before they turned 18 was motivated by her desire to get even with the Department of Family and Community Services.

Ms Ryan read out in court Ms Holt's conversation with Bobby about kidnapping his younger brother Billy: 'F*** them. Yeah, f*** them. I just hope they don't take him back because he is younger. But they will try'.

Ms Ryan said the hundreds of phone calls Ms Colt had made to Bobby since five of her children were removed from her care in 2012 demonstrated an extremely strong bond between the mother and son.

An intricate web of incest was discovered - with 13 children the direct descendants of Betty Colt

Ms Colt had been aware of the 'incest, consanguinity ... and sexual abuse' going on in her family when they were engaged in 'communal living' on the squalid farm block.

The magistrate said Bobby and Billy had showed marked improvement in personal hygiene and health since being taken from their mother, but that Betty Colt had been desperate to get her children back.

Billy had wanted to stay in care but 'would have been coerced by the sheer force of his mother's will'.

In one conversation with Bobby, she told him: 'I'll get you home and make it f***ing hard for them to get you out', the court heard.

Ms Ryan quoted Ms Colt's conversations with Bobby in October last year when she was planning to taker her sons to South Australia.

'I ain't giving up until I get everyone of you home. I won't stop,' Ms Holt told Bobby.

'Don't let them know until the day you go.'

She and her 13 children were among 38 inter-related adults and children discovered two years ago living in incestuous relationships and filthy conditions in the hills surrounding a picturesque farming community nestled in a valley southwest of Sydney.

Their real identities have been suppressed and the family name ‘Colt’ given by the court to protect the identities of the children.

A total of 12 inbred, illiterate and malnourished children were taken from the camp and placed in care.

Among Betty Colt's children are five who were likely fathered by her own father or brother.

Her 35-year-old sister Martha is the mother of four living children which were fathered by her own brother, Charlie; a fifth child died in infancy, possibly as a result of congenital deformities caused by having related parents.

Betty Colt was convicted in September of attempting to kidnap two of her sons from their foster parents

Sister and brother Martha and Charlie slept nightly in a 'marital' bed inside a tent on the squalid farm, where open buckets of faeces and urine lay about and where their children - brothers and sisters - had sex with each other.

A strike force made up of members of the NSW child abuse squad - spearheaded by detective inspector Peter Yeomans and detective sergeant Kirsty Hales - was formed after the case of the Colt family was heard in the NSW Children's Court.

Children as young as ten years old belonging to Betty Colt or her sisters were engaging in sex with their underage aunts and uncles.

Betty's sons Billy and Bobby were among five of her 13 children taken from her in 2012 because they were the product of a sexual union between Ms Colt and most likely her father, Tim.

The children had facial deformities, could not speak intelligibly, did not know what a toothbrush or toilet paper were. They were living in filthy caravans and tents with no running water or electricity.

Martha Colt's children were profoundly deformed and neglected.

The first indication the family was living in depraved and squalid conditions came when a child was overheard talking about incest at school

Martha has five living children - two girls, Nadia and Ruth, and three boys, Karl, 13, Jed, 15 and Albert, 16. Police applied to Parramatta Court to prevent Martha having contact with the youngest of her five children, Ruth, 10, and Nadia, 8.

That court heard Nadia, who was just six years old when the family commune was uncovered, was having sex with her brothers, had sticks inserted into her by her maternal uncle Charlie - who is actually her father - and both her father and mother had taken intimate photographs of her.

Nadia was 'neglected and malnourished, unable to bathe' her hygiene skills were 'primitive'.

She 'didn't know how to use a toilet, what toilet paper was, had not seen a toothbrush before. Her teeth were decayed. She had speech delay ... was delayed educationally'.

Ruth, then aged nine years old, was 'drastically underweight', 'was unable to bathe herself, did not know how to use a toilet or what toilet paper was'.

Ruth required urgent dental attention, 'her speech was fragmented and stunted, her features were dysmorphic and she could not read or write'.

Of the 12 Colt children from the whole Colt clan who were later proven by genetic testing to have 'homozygosity', or identical gene patterns in both parents, seven were found to have closely related parents. Four of those seven children were Martha's.

The NSW Children's Court took the rare step in December last year of revealing the actions it took to remove children from the Colt family.

Four generations of intimate relations among the Colts had taken place over decades in South Australia, Victoria, Western Australia and finally in NSW.

Four generations of intimate relations had occurred over decades in locations around Australia

Moving state to state, possibly to evade detection, the scandal only came to light because of a schoolyard conversation involving one of the children living in the hills who did attend school.

One of the Colt family children was overheard saying at the school, 'My sister is pregnant and we don’t know which of my brothers is the father’.

The remark triggered the raid by officers from the child abuse squad along with Family and Community Services officers who turned up at the block, which lies around 30km out of the town between large established farms and untamed scrub.

They found the adults and children living in two filthy caravans, two sheds and tents on an unsewered block with no plumbing.

Dirt caked the surfaces of stoves and cooking facilities, rotten vegetables lay in a refrigerator and a kangaroo was sleeping on one of the children's beds.

Exposed electric wires, bags of rubbish and chainsaws lay about.

There were no toilets, showers or baths. The children were unwashed, wore dirty clothes and almost all had fungal infections on their feet.

They were shy and made little eye contact, and the welfare officers learned that few were capable of intelligible speech.

Betty's son Bobby had a walking impairment, severe psoriasis and needed urgent dental work.

His speech was not understandable. He wet and soiled the bed and his learning ability was at kindergarten level.

Betty's other teenage son, Billy, was underweight and not growing properly, had hearing and sight problems, spoke unintelligibly, had an intellectual disability and could barely read or count.

Kimberly Colt, 14, Betty's granddaughter, was underweight and unable to clean her teeth, use toilet paper or comb her hair.

She had urgent dental problems, hearing, speech and sight issues and was unable to read or write. She threatened to cut off a caseworker's fingers.

Betty's son Brian, 12, did not understand showering and had extensively decayed teeth, and borderline normal hearing. His eyes were misaligned and he could not read, write, or recognise numbers.