In what some are describing as a landmark case, a U.K. man who used AI to turn normal pictures of children into sexual abuse imagery has been sentenced to 18 years in jail.

Hugh Nelson, a 27-year-old from Bolton, used the app Daz 3D to create 3D “characters” from innocent photographs of kids. In some cases, people had commissioned the images, The Guardian reports, supplying photos of children with whom they had contact in real life.

Nelson sold the commissioned child sexual abuse images on online forums, making about £5,000 (~$6,494) over 18 months. He was caught after telling an undercover cop he charged £80 (~$103) to create a new character using supplied pictures.

Nelson was later found guilty of encouraging the rape of a child under 13, attempting to incite a boy under 16 to engage in a sexual act, distributing and making indecent images, and possessing prohibited images.