The Colt incest family was adept at fleeing across borders overnight to avoid arrest by police pursuing charges of inbreeding and child abuse, a court has heard.

The court also heard that the oldest of three Colt family matriarchs has been bashed in prison and that the inbred children have escaped from care to rejoin the clan since police broke it up.

The Colt family, eight of whom were arrested in April over child sex, incest and other charges had "a history of coercive tactics to avoid detection", a DPP prosecutor told Central Local Court.

"The children and young adults have cognitive or physical disabilities related to their genetics which makes them extremely vulnerable to coercion to go back to the family," Mardi Cartwright told the court today.

One of the eight Colt family members is arrested in South Australia in April and deported back to NSW. Photo / NewsCorp
One of the eight Colt family members is arrested in South Australia in April and deported back to NSW. Photo / NewsCorp

She said the Colt adults went to great lengths to keep their inbred children from giving evidence to authorities and "a number of children have absconded" from state care.

Cartwright was addressing a bail hearing by Rhonda Colt, one of three matriarchs and eight Colt family members arrested in tri-state raids in April.

Rhonda Colt, who looked drawn and weary sitting a prison video cubicle at Silverwater Correctional Centre, wept during the hearing.

Colt is a court-appointed pseudonym for the family to protect the identity of children.

Members of the family previously told authorities the sordid saga of the incestuous clan began in New Zealand early last century when a June Colt was born to parents who were siblings.

Four generations of incest allegedly began after "Tim and June Colt," a brother and sister emigrated from New Zealand in the 1970s. In 1966, June, the product of brother-sister incest, and Tim married and had seven children together: Martha, Frank, Paula, Cherry, Rhonda, Betty, and Charlie, before moving to Victoria in the 1970s.

Rhonda Colt, 51, is the oldest of five Colt siblings and three of their adult children arrested after a five year investigation.

In 2013, 38 members of the now notorious Colt clan were found living in a squalid bush camp with no electricity, sanitation or running water in the hills behind the NSW town of Boorowa.

The children had misshapen features, could not speak intelligibly or walk properly, did not know how to use a toothbrush, did not know what toilet paper was and were engaging in sex with each other.

An investigation by the NSW Child Protection Squad's Strike Force Hermoyne has resulted in the arrests of the Colt eight on charges including perjury, incest, indecent assault and sexual intercourse with a child under the age of 10.

The Colt clan had scattered interstate from country NSW after police removed 13 children who were the product of sexual relations between a father and daughter, sister and brother, uncle and niece or other relatives.

"The family has been known by police to move to avoid the service of legal documents," Cartwright told Magistrate Beverly Schurr.

She said the Colts had ties in Western Australia, South Australia and Victoria and Rhonda Colt "has an understanding of police methodology and knows how to avoid police".

"[She] is known to travel overnight to avoid apprehension," Cartwright said.

"There is evidence of generational and interfamilial abuse and a history of coercive tactics to avoid detection … and the notice of police."

Cartwright said the mentally and physically impaired children could be lured back into the family fold at placed at risk of "physical, emotional and sexual abuse".

Rhonda Colt had been living 100km northeast of Perth with two male relatives when police charged her with perjury and extradited all three back to NSW.

Police charged a 36-year-old with four counts of having sexual intercourse with a child under 10, two of indecent assault, and one of having sex with a child aged between 10 and 14.

A 48-year-old man was charged with having sexual intercourse with a child under 10 years.

Other Colt family members were arrested in the NSW town of Griffith and South Australia's Riverland region.

Only one of the eight, matriarch Betty's 34-year-old daughter Raylene has been granted bail on her single perjury charge.

This tent, which slept three children, was set up inside a large steel shed in the family camp in NSW. Photo / Supplied
This tent, which slept three children, was set up inside a large steel shed in the family camp in NSW. Photo / Supplied

Rhonda Colt's solicitor offered to have his client report twice daily to police if freed on bail, but Magistrate Schurr said the risks were too great.

Mardi Cartwright told the court that Rhonda Colt's defence had claimed she had been assaulted in prison, but had provided no evidence for the bail application.

"This is a serious example of perjury," Schurr told the court.

"Questions about the welfare of young children were not honestly answered.

"Children and grandchildren have been placed in care and some wish to remain in contact with family.

"There could be contact with [Rhonda Colt] and witnesses."

After Schurr refused bail, Rhonda Colt stood up in the prison video cubicle and held her head in her hands and sobbed.