The man who allegedly shot dead at least 10 people at a Buffalo, New York, supermarket on Saturday may have been preoccupied by the so-called “great replacement” conspiracy theory. A sprawling propaganda document released online under his name in advance of the attack obsessively references that theory. Authorities have yet to confirm the authenticity of the document, but if it was indeed written by the killer, it further exposes the deadly consequences of white supremacy.