A serial sex offender was caught with “some of the worst” child abuse images ever found by experienced investigators.
Robert Nash was arrested last December after raids at his home and his mother’s house in Dumfries.
The 51-year-old had a haul of 75,159 still and moving images of “child sexual exploitation” of young boys.
The High Court in Glasgow heard how Nash, also known as Wilkinson-Brown, already had a string of convictions for similar crimes.
He had been jailed in Scotland and in England, including two five-year jail terms.
Nash was freed early in late 2016, but his last prison sentence was not due to expire until 2023.
The hearing was told police had information two internet IP addresses had been linked to indecent images being accessed.
When officers turned up at Nash’s home, he confessed: “I want to come completely clean. There is a memory stick in the drawer.”
Police then also became aware there were other storage devices kept at his mother’s house in the town.
Prosecutor Euan Cameron said two USB sticks and a memory card were then discovered hidden in a Spiderman game box.
The footage was “encrypted”, but Nash gave police the code to access it.
Mr Cameron added: “The material was considered some of the worst encountered by (investigators).”
Lady Poole remanded Nash in custody as sentencing was deferred for reports.