A Nazi sympathizer who threatened to butcher a Hispanic woman and boasted that President Trump would wipe out nonwhites in a “racial war and crusade” was arrested on charges of making threats, the F.B.I. said on Tuesday.

Prosecutors said that the suspect, Eric Lin, 35, sent a barrage of chilling and gruesome Facebook messages to the unidentified woman, who lives in Miami. Mr. Lin was arrested on Friday in Seattle, where he had recently moved from Clarksburg, Md., but was charged in Miami.

“This is a RACE WAR and ALL of you will DIE!” Mr. Lin wrote to the woman on Facebook in early June, according to a criminal complaint. The next day, he wrote, “You want to see what a real Nazi can do?” adding later that he was operating under the authority of Hitler. In July, he wrote that “I thank God everyday President Donald John Trump is President and that he will launch a Racial War and Crusade.”

Mr. Lin’s arrest was the latest example in a series of what the authorities say are racially motivated threats and possible attacks by violent domestic extremists that have received renewed attention amid a spate of mass shootings and other violence. “Domestic violent extremists collectively pose a steady threat of violence and economic harm to the United States,” the F.B.I. director, Christopher A. Wray, said last month at a Senate hearing.