Sheriff Arpaio's Office Says Mail Bomb Was Strong Enough to Maim or Kill Police have person of interest in mind, bom neutralized by water cannon.

April 12, 2013 -- A suspicious package addressed to controversial Arizona Sheriff Joe Arpaio contained a bomb that was powerful enough to maim or even kill him, his office said today.

"Had someone opened that package, it would have caused a major explosion and caused serious physical injuries, burns and maybe death," Maricopa County Sheriff's Office spokesman Jerry Sheridan said at a press conference. "That was a very serious threat, it was labeled to come here to this building and be opened by Sheriff Arpaio."

"Packages do wind up on the sheriff's desk," said Sheridan.

The mail bomb was discovered Thursday by a Flagstaff postal worker who noticed what they thought was gunpowder residue coming from outside the package. The Flagstaff police department bomb squad X-rayed the package, noticing what appeared to be an explosive device inside.

"There were wires and a container in the device," said Sheridan.

The device was disarmed when the police department bomb squad blasted it apart with a water cannon.

Investigators are working now to piece together the device to determine the exact explosive contained in the package, Sheridan said.

The spokesman said the sheriff's office has a person of interest in the case who they are trying to locate, and that they are cooperating with the U.S. Postal Inspector, the FBI, and the Bureau of Alcohol, Tobacco, Firearms and Explosives in the investigation.

Sheridan said although death threats against Arpaio are something the office deals with on a regular basis, this possible bomb threat was something that was "brought to the height of seriousness," and that the office had never received an explosive device in the mail before.

Arpaio said he wouldn't be intimidated by any threats, and would continue to do his job.

"I'm not leaving this office no matter what they do, what they say, I'm staying," Arpaio said. "That's my message to all these people who don't like this sheriff."

The explosive device follows the killings of another law enforcement officer and prosecutors. Two prosecutors have been gunned down in Kaufman County, Texas, since January. And last month, Tom Clements, chief of the Colorado prison system, was killed in his home.

Arpaio, dubbed "America's Toughest Sheriff," was elected sheriff of Maricopa County in 1992 and since then has garnered national headlines with his views on immigration, prisoners' rights and gun control.

Arpaio's latest controversy came weeks after the Newtown, Conn., mass shooting, when he deployed armed volunteers to patrol schools in the Phoenix metropolitan area.