A former federal public servant's children were "completely at his mercy" when he carried out "repugnant abuse", which included filming himself raping his toddler.
That is what Justice David Mossop said in the ACT Supreme Court on Thursday afternoon, when he sentenced the north Canberra man to 14 years and five months in jail.
The man sat rocking back and forth, with his head bowed, as Justice Mossop recited graphic details of his crimes and ordered him to serve at least eight years and eight months.
He had previously pleaded guilty to 24 child sex charges, which included persistent sexual abuse, incest, acts of indecency and offences involving the production and possession of exploitation material.
The man landed on the radar of police in February 2022, when the Australian Centre to Counter Child Exploitation detected his internet protocol address accessing abuse material.
When investigators raided his home and seized items, including computers and a hard drive, the man admitted downloading child abuse material but denied offending against his own children.
However, a subsequent review of the offender's devices identified nearly 16,000 child abuse material files, some of which showed him sexually violating his toddler daughter.
This abuse took place on seven occasions in 2018.
The offender's son, who was three at the time, was present during one of these occasions.
The files the man had downloaded from the internet, meanwhile, featured no less than 800 child victims aged between two months and 14 years. Some depicted the victims being tortured.
One of the offender's computers also contained a "paedophile's handbook", which the court has heard included advice on how to speak to police if caught with child abuse material.
On Thursday, Justice Mossop said he had viewed a sample of the depraved files the offender had personally produced.
The judge said this had "served to reinforce the gross abuse of the parent-child relationship".
Justice Mossop noted the man's children were, because of their ages and relationship with the offender, "completely at his mercy" during the offending period of six-and-a-half months.
"Many grave sexual acts occurred over that period," the judge said, describing the crimes as "a repugnant abuse of the offender's parental role".
Despite this, he did not accept prosecutor Skye Jerome's submission that the offending fell into the category of a worst-case scenario.
His reasons for this conclusion included that the offending was "confined in duration" and did not involve overt coercion or violence.
He also said there was no evidence the offender's children knew or understood what was occurring.
The court heard the offender was a university-educated man, who had worked in the federal public service in information technology roles.
Justice Mossop said his behaviour while remanded in custody had been "positive", noting the offender had worked as a sweeper, in the bakery and as a library assistant.
The judge ultimately imposed the lengthy jail sentence and ordered that the 36-year-old offender's computers, hard drive and phone, the latter of which was used to produce abuse material, be forfeited to the Commonwealth.
With the offender's sentence backdated to account for time already served behind bars on remand, he will become eligible for parole in January 2031.
