Joe Arpaio, the sheriff of Phoenix’s Maricopa County, is infamous for his harsh crackdowns on undocumented immigrants. But even he says Donald Trump’s anti-Mexican rhetoric has crossed a line. “I agree with him on one aspect, that we do have rapists and murderers coming across the border,” Arpaio told Fusion anchor Jorge Ramos in an interview. “But when you mention rapists and murders, okay, I don’t think the majority of people from Mexico are rapists and murderers.” “I think Mr. Trump was frustrated at the many crimes committed in this country by those from Mexico, including coming across the border...