20-year-old German-Iranian former medical student faces 123 charges of murder, child rape, and abuse. Arrested in affluent Hamburg home after FBI tip on child porn. Police found 85,000 files and 600 torture videos. Led ''764'' network labeled US terrorist group. Forced kids from Germany, UK, US, Canada to mutilate for sexual pleasure. Drove 13-year-old US boy to suicide via Finnish girl intermediary. Manipulated Finnish minor with love-contempt mix into recruiting victims. Joined Instagram suicide chat to push boy over edge and share video. Held in youth prison under max security. German law complicates case since suicide not punishable. Prosecutors prove ''indirect perpetration murder'' through others. Offenses described as beyond human imagination. Additional parent reports pouring in. Investigations target more victims.