Arpaio has responded by housing inmates in tents, clothing them in pink underwear and serving green and blue meat.
Rep. Raul M. Grijalva (D-Ariz.) said the sheriff's department could not be reformed unless Arpaio stepped down. "He's the one who made himself a national figure by violating people's rights," Grijalva said.
Paul Charlton, a former U.S. attorney in Arizona who represented two local government officials who butted heads with Arpaio, only to be retaliated against, said of the sheriff: "If not for the federal government, this county would be run like a fiefdom."
In recent months, there have been some signs that Arizonans are weary of Arpaio's get-tough approach on illegal immigration. Earlier this year, Arpaio ally Russell Pearce, president of the state Senate and author of SB 1070, the state's controversial law targeting illegal immigrants for deportation, failed to push through a raft of anti-illegal-immigration bills. In November, Pearce was booted from office in a recall election.
The same group that targeted Pearce, Citizens for a Better Arizona, has recently turned its attention to Arpaio.
Prosecutors said Arpaio often was personally involved in abuses. In 2008 he received a letter expressing dismay that none of the employees of a local Sun City McDonald's restaurant spoke English. The sheriff wrote a note thanking the writer "for the info" and promising to "look into it." Two weeks later, at Arpaio's request, his deputies conducted an immigration operation in Sun City.
That same year, after receiving a letter about day laborers in Mesa, Arpaio responded, "I will be going into Mesa." Soon afterward his deputies conducted several crackdowns on crime in that community. When another letter arrived complaining of "dark skin" people in Phoenix, Arpaio passed it to his command staff with orders to "have someone handle this."
Powers reported from Las Vegas. Staff writer David G. Savage in the Washington Bureau contributed to this report.