On October 16 2020, a secondary school teacher named Samuel Paty was beheaded with a meat cleaver in the street of a small town 20 miles down the Seine from Paris. 1/x

Paty's murderer, a young Chechen refugee, had never met the teacher. The killer was incited to the crime by a multi-day campaign of defamation and disinformation on French social media. 2/x

For 5 years, Paty had taught his classes a unit on free speech and its limits in a democratic society. As part of the discussion, he showed his students some of the famous Charlie Hebdo cartoons - after inviting those who might be offended to leave and then rejoin the class. 3/x

One parent of one student - not the student herself - then set in motion a campaign of denunciation against Paty. And the result was a crime that shocked France and pulled tens of thousands to vigils and protests. 4/x

France has suffered terrible crimes in the name of religion before the Paty killing. We're only 5 years from the horrifying nightclub attacks that killed 130 in November 2015. But past attacks caught France by surprise. This murder announced itself in advance. 5/x