-- by Jerry Markon and Stephanie McCrummen, The Washington Post:

A federal investigation of a controversial Arizona sheriff known for tough immigration enforcement has intensified in recent days, escalating the conflict between the Obama administration and officials in the border state.

Justice Department officials [1] in Washington have issued a rare threat to sue Maricopa County Sheriff Joe Arpaio [2] if he does not cooperate with their investigation of whether he discriminates against Hispanics [3]. The civil rights inquiry is one of two that target the man who calls himself "America's toughest sheriff." A federal grand jury in Phoenix is examining whether Arpaio has used his power to investigate and intimidate political opponents and whether his office misappropriated government money, sources said.

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