The suspect in the massacre that left 51 Muslims dead in Christchurch, New Zealand, allegedly posted a white nationalist screed and link to his Facebook live feed on 8chan, a far-right message board and notorious bastion of hate speech. The suspect in the shooting at a synagogue in Poway, California, that killed one person and injured three, allegedlyposted a racist and antisemitic “open letter” on 8chan. And the suspect in Saturday’s attack at a crowded Walmart in El Paso, Texas, which claimed the lives of at least 20 people, is believed to also have posted a white nationalist rant on the platform.

If the connection between the 21-year-old suspect in Saturday’s massacre and the 8chan document is confirmed – and law enforcement sources told NBC News that they are “reasonably confident” that they are linked – then the El Paso attack will mark the third mass shooting in less than six months that was announced in advance on the message board. The first targeted Muslims, the second Jews, and the third appears to have been aimed at killing Latinos.