Two years ago this week, a gunman in El Paso, Texas, killed 23 people in a Walmart — most of them Latino.

The white man charged with murder allegedly told police he drove 11 hours to the U.S.-Mexico border city with the intention of targeting Mexicans. He reportedly complained about a “Hispanic invasion” of Texas and warned that the U.S. was in the process of a “cultural and ethnic replacement.”

That language echoes the writing of an infamous and influential white nationalist who died at age 85 just weeks before the El Paso massacre. John Tanton was an eye doctor from northern Michigan, but he was better known to some as "the architect of the modern anti-immigrant movement."

Here & Now's Peter O'Dowd speaks with Mark Potok of the Center for Analysis of the Radical Right.