Eight people have gone on trial in Paris accused of encouraging the killer of Samuel Paty, the teacher who was beheaded on the street outside his school four years ago.
Abdoullakh Anzorov, the young man of Chechen origin who wielded the knife, is dead - shot by police in the minutes after his attack.
So the trial is less about the murder itself, and more about the circumstances that led to it.
Over seven weeks, the court will hear how a 13-year-old's schoolgirl lie span out of control thanks to social media, triggering an international hate campaign, and inspiring a lone mission of vengeance from a self-styled defender of Islam.