A father-of-two who duped his young sisters-in-law into being his sexual playthings and then turned them into fantasy figures for thousands of other internet paedophiles has been jailed for 13 years and put on the Sex Offenders Register for life.
Judge David Smyth QC told the 34-year-old self-confessed paedophile that "the public interest properly demands a condign sentence" for his campaign of evil abuse of the sisters, made worse by the fact he had filmed and distributed that abuse.
The Downpatrick Crown Court judge also rejected defence claims that the "laughing" computer expert posted his perverted exploits online on the web as "a huge cry for help... he was almost begging to be caught".
Last week the court heard his systematic grooming of the schoolgirl sisters was such they did not realise he was simultaneously abusing and secretly videoing them until a friend spotted them on an adult porn site.
In all the man, who cannot be named to protect the identity of his victims, pleaded guilty to a total of 40 charges, including possessing more than 15,000 indecent images, voyeurism, indecent assault, sexual assault and gross indecency, and inciting a child to commit gross indecency.
Prosecution lawyer Samuel Magee said "each and every offence is characterised by and centred around sexual exploitation of children for his own sexual gratification, and as a consequence of his actions, doubtless thousands of others" on the internet.
Mr Magee said the man first began abusing one of the girls in the run-up to marrying her sister, after she told him she wanted to look her best as a bridesmaid.
Sometime after the wedding he turned his perverted attentions on the younger girl after offering her lifts home from school.
The lawyer revealed that not only did he sometimes secretly film them as he abused them, but he also planted a video-keyring so he could "clandestinely" capture them showering.
But in August 2011, to the shock and horror of the girls and their family, the depravity to which the sisters were subjected was uncovered when a friend stumbled upon a website with an entire profile "solely dedicated" to the sisters.
Mr Magee said, "to his credit", he immediately raised the alarm, leading to the man's arrest and the thousands of indecent images recovered from his computers, some of which held a majority of images of the sisters being abused.
Judge Smyth said he notified the girls' family, and for this he "deserves high praise".
Defence QC Donna McColgan said while it was of little consolation to the girls and their family, her client felt nothing but shame and disgrace for what he has done and deserved credit for his guilty pleas and admissions.
Ms McColgan said almost from the start his opening gambit to police was to tell them: "I know it sounds strange, but I'm glad this day has come... I have no excuse."
She also revealed that since his arrest he has been paying for private sessions with a psychiatrist in jail by way of treatment, and that in terms of his own life he now knows he has lost every thing.