Raymond John Luke was arrested at his home in Bidill, in western Sydney, in July 2020 when police seized a laptop and two computer towers.

Local authorities were alerted by Interpol Moscow about a network where Australian users were suspected of sharing child abuse material.

Luke is charged with two counts of using a carriage service to transmit child abuse material and three of possessing or controlling child abuse material obtained using a carriage service.

When he appeared in Penrith Local Court in May, the case was referred to the District Court to determine his fitness to be tried.

Judge Donna Woodburne on Thursday found he was unfit to stand trial after considering unanimous reports referring to his neurocognitive disorder and his secondary depressive condition.

Experts noted his very limited verbal comprehension skills and his significant memory impairments.

He would likely find it difficult to follow the flow of events in a court room or give a consistent account to his lawyers.

Luke was also said to have been subject to a number of stressors including "persecution from the local community" about the charges.

After ruling he was unfit, the judge found there was a prima facie case against Luke after taking into account the crown evidence "taken at its highest".

In arguing against the charges being dismissed, the Crown said they were not of a trivial nature and cited "the highly depraved and graphic nature of the material".

Judge Woodburne declined to dismiss the charges.

The third step in the proceedings involved ruling on whether he is likely to be fit to be tried within a 12-month period.

She adjourned the case for mention on December 9 to enable brain injury and other testing to be carried out by a geriatrician and other experts.

Australian Associated Press