Arizona authorities intercept explosive device addressed to Maricopa Sheriff Joe Arpaio

(CBS/AP) PHOENIX - An explosive device addressed to Arizona's Sheriff Joe Arpaio was intercepted late Thursday and authorities are investigating who sent the package to the self-proclaimed "toughest sheriff in America" known for his strict treatment of jail inmates and cracking down on undocumented immigrants.

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The device was intercepted in Flagstaff and was addressed to Arpaio at his downtown Phoenix office, the Maricopa County Sheriff's Office said in a statement. The package appeared suspicious, so it was X-rayed and the device was detected. A bomb squad team neutralized the explosive.

Arpaio's chief deputy, Jerry Sheridan, told The Arizona Republic that investigators believe the package was picked up on Thursday at a rural Post Office box. Flagstaff is about 140 miles north of Phoenix.

Initial reports indicated that the package was a box that may have been damaged in transit and leaked gunpowder, said Tom Mangan, a spokesman in Phoenix for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.

Following the killing of a West Virginia sheriff last week, Arpaio said elected law enforcement officials across the nation seem to be targeted.

A national hero to conservatives on immigration issues, Arpaio has been the target of numerous threats in the past, which prompted the need for a security detail for the lawman.

A campaign to recall Arpaio began just weeks after he started his sixth term in January.

Critics contend Arpaio should be ousted because his office failed to adequately investigate more than 400 sex-crimes cases, allegedly racially profiled Latinos in its trademark immigration patrols, and has cost the county $25 million in legal settlements over treatment in county jails.

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