Federal authorities began a probe after receiving complaints for months that Maricopa County deputies are discriminatory in their enforcement of federal immigration laws, the Arizona Republic reported Wednesday.
The newspaper said the Justice Department's Civil Rights Division on Tuesday notified Maricopa County Sheriff Joe Arpaio that it is probing whether deputies are engaging in "patterns or practices of discriminatory police practices and unconstitutional searches and seizures."
For his part, Arpaio denies that deputies are illegally profiling as part of his immigration crackdowns.
"We have nothing to hide," he was quoted by the newspaper as saying.
The newspaper noted that last year Phoenix Mayor Phil Gordon asked for a federal investigation of possible civil-rights abuses by the sheriff. Last month, four key Democratic members of the U.S. House Judiciary Committee asked Attorney General Eric Holder and Homeland Security Secretary Janet Napolitano to investigate Arpaio.
Arpaio, who was re-elected to a fifth term in November, called the investigation politically motivated and vowed to continue to arrest illegal immigrants.
"I am not going to be intimidated by the politics and by the Justice Department," Arpaio said. "I want the people of Arizona to know this: I will continue to enforce all the immigration laws."