14:01 BST
Image source, Getty ImagesAlthough investigators believe as many as 3,500 children were targeted; this case focused on 70 of them in order to provide a manageable caseload for the court.
In 2019, it was confirmed that the Police Service of Northern Ireland had set up a “dedicated team” to specifically examine the McCartney case, due to the number of potential victims.
Identifying the alleged victims had become a “mammoth task”, an earlier court was told, with the investigation stretching as far as New Zealand.
The court heard that, initially, 12 computer devices were seized from McCartney following his arrest.
It was explained that these devices had the capacity to emulate other computers, giving the operator the ability to make contact with four times as many victims.
“Each emulator has 760 folders, and each of these folders identifies one victim,” a prosecuting solicitor said.
“There is a small sample being brought forward for prosecution, which is just the tip of the iceberg.”
In total 64 devices were found at his house in the rural Lissummon Road area outside Newry during four separate raids.
These devices contained thousands of images of abuse.