Targeting students and other young men, he would leave his apartment late at night, homing in on those who looked drunk or vulnerable.
After striking up conversation, he would invite them back to his nearby flat, with offers of drinks or the opportunity to charge their phones.
Once there he would spike them with the class C party drug GHB, which would quickly render them unconscious.
He would then rape or sexually assault them, often numerous times, filming the attacks on his mobile phone for his own perverted posterity.
The vast majority of his victims said they had no recollection of what had happened and believed they had simply passed out in the flat after drinking too much.