An investigation by the Department of Internal Affairs and Mega Ltd into two public links that were circling the internet began in late 2019.
The investigation led them to discover 310 New Zealand users of Mega who had saved the file in their account.
One of these accounts, under the name John Parker, was Buckley.
As described by senior inspector of publications at the department, John Peacock, Mega is a "secure cloud storage" site, allowing people to store their files online.
While police found no evidence of objectionable material on Buckley's devices when they executed a search warrant in 2020, four copies of the file labelled "Nunu" were found in the rubbish bin of his Mega account.
Inside that folder were more than 11,000 videos and images of child sex abuse material, featuring babies to teenagers.
Counsel Brendon Stephenson said his client did not know what the file was when he first saved it to his account.
Buckley had been searching for a specific kind of pornography — the domination of men dressed as babies by women — when he came across it.
However, once he realised what it was, he "deleted out of it", the court heard.
In his evidence, Buckley said he remembered Mega because he was required to create an account before viewing the material, something both Peacock and chief compliance officer of Mega Ltd, Stephen Hall, contradicted.
The link was open to anyone who had access to it, said Hall.
The court heard Mega's default view was a "mosaic thumbnail", displaying a snapshot of the video or the image alongside the file name, meaning Buckley would have been able to see what the material was very quickly.
"It was readily apparent what the nature of the material was," Crown prosecutor Richard Smith said.
While it was accepted Buckley imported the material and that the material was objectionable, the Crown had to prove that Buckley saved the files intentionally, knowing what they were, and voluntarily kept them in his account.
Stephenson said the three repeated times "Nunu" was saved into his account were because he regularly searched for pornography, and landed on the same forum sites, where he must have "accidentally" clicked on it.
Even if it was accepted he "accidentally" stumbled upon the link on June 8, "he had no business going back on the 12th and the 19th", Smith told the jury in his closing statements.
That they were imported four times and the amount of time that the videos stayed in his account spoke to "deliberate action", the court heard.
Smith said Buckley revisited the same link because he knew exactly what he was looking for — child sex abuse material — and where to find it.
"You'd have to believe he's the victim of such extraordinarily bad luck to think he's not guilty."
Judge Michael Turner remanded Buckley on bail to be sentenced on September 2.