Arizona Sheriff Joe Arpaio fired back at one of his most outspoken critics, Al Sharpton, on Wednesday, according to Arpaio of Phoenix was asked by Sharpton to resign in light of the sheriff’s controversial immigration policy. In a letter dated June 3, Arpaio told Sharpton he refuses to step down from his post. Arpaio said he welcomes Sharpton to tour his facilities and see firsthand how he operates his programs.—BB