A former public servant has been forced to collect garbage for a living after embarking upon a "highly risky" vigilante mission to rid the internet of child abuse material.
David John Horner was sentenced in the ACT Supreme Court on Tuesday to an 18-month jail term.
But he will not serve a day behind bars, with Justice Belinda Baker making an immediate recognisance release order that suspends the sentence.
Horner had previously pleaded guilty to charges of using a carriage service to access and possess child abuse material.
Justice Baker said the charges arose from an Australian Federal Police raid of a Canberra home, where Horner lived at the time, in November 2021.
Then working in the ACT public service, Horner was at home with his family when investigators turned up with a search warrant.
Police ultimately seized two devices, including a Dell computer that was later found to contain three videos that met the definition of child abuse material.
A forensic examination showed the videos, which depicted the abuse of two children aged between three and six, had been accessed between August 2018 and April 2019.
Investigators also located on the computer a document titled "complaint".
It contained 64 reference numbers, 50 of which matched anonymous reports made to the eSafety commissioner under the online content scheme.
The reports, made between March 2013 and June 2018, alerted authorities to 247 website addresses relating to "child sexual abuse/child abuse/paedophile activity".
Some of the websites were only accessible using the dark web.
Horner, who was 48 at the time of the search, initially told investigators he could not understand why child abuse material would be on his computer.
However, when he was subsequently arrested in April 2022, he informed police of the "complaint" document and said it contained details of child abuse material he had reported.
On Tuesday, Justice Baker said Horner's life had changed significantly since his arrest.
The changes included the offender separating from his wife, being placed on leave from his public service job and later resigning, and moving to Brisbane to live with his father.
Justice Baker said Horner had, since leaving the public service, earned a living by collecting garbage, washing dishes and working in a supermarket.
She said he had participated in a pre-sentence report interview and sought to "disassociate himself from the offending", but he had since voluntarily sought treatment and written a "powerful" letter to the court in order to demonstrate his increasing insight into his crimes.
Horner was "devastated", the judge said, by the realisation his actions in accessing and possessing child abuse material potentially fuelled a market for it.
Addressing Horner's motivations, the judge said the offender had experienced childhood trauma and had told a psychologist he "wanted to be a vigilante".
The psychologist thought "deciding to go on a vigilante mission to seek out and report all the child abuse material that he was able to find was a highly risky activity".
Justice Baker accepted the psychologist's opinion and said Horner's vigilante behaviour needed to be discouraged and denounced.
However, she accepted his moral culpability was reduced by his childhood experiences and mental illness.
These were some of the exceptional circumstances Justice Baker found to exist in Horner's case, with others including the limited amount of material he had possessed and accessed.
A finding of exceptional circumstances was the only thing that could have spared Horner time behind bars under the Commonwealth legislation that criminalises child abuse material.
"This sentence, for this form of offending, is rare," Justice Baker told Horner of the immediate recognisance release order.
The judge added that it was "absolutely critical" for Horner to continue getting mental health treatment, warning exceptional circumstances would not be found again if he reoffended.
