Three years ago today a chemical attack in Khan Sheikhoun killed over 80 people in a most horrific way. Syria & Russia denied responsibility. And so began @nytimes visual investigations: how did their claims stack up to facts. w/ @markscheffler & Natalie R https://nyti.ms/2q4cYz4 

A year later another chemical attack killed a large number of people in Douma. Syria and Russia’s denials became more forceful and creative. But our reporting too had developed in sophistication and found the truth. w/ @ForensicArchi @bellingcat assists.