But after a pull-no-punches news conference in which he linked the shooting in Tucson to a poisonous underlying political atmosphere, the Pima County sheriff may soon become known nationally as the anti-Joe Arpaio.
"When you look at unbalanced people, how they respond to the vitriol that comes out of certain mouths about tearing down the government. The anger, the hatred, the bigotry that goes on in this country is getting to be outrageous," said Dupnik, referring to the troubled suspect, 22-year-old Jared Loughner.
Dupnik said Arizona, embroiled over the last year by bitter divisions over illegal immigration and health care reform, has "become the mecca for prejudice and bigotry."
Many officials have been threatened, including Giffords, the federal judge killed by her side and Dupnik himself. The sheriff called that a "sad thing," and said, "Pretty soon, we're not going to be able to find reasonable, decent people who are willing to subject themselves to serve in public office."
Dupnik, who turns 75 Tuesday, became an instant hero among liberals, who drew a sharp contrast to that other septuagenarian sheriff over in neighboring Maricopa County.
Arpaio, 78, has branded himself "America's toughest sheriff." His harsh and unapologetic tactics to catch illegal immigrants have made him a magnet for controversy who has been accused of trampling civil rights and inciting hate. But they also have made him a tea party star and a long-shot candidate for the 2012 Republican presidential nomination.
While the Maricopa County sheriff couldn't have been happier when Arizona passed the nation's toughest crackdown on undocumented immigrants, Dupnik was appalled.
A Democrat, Dupnik called the law "a national embarrassment" and wrote in the Wall Street Journal that it was "unnecessary ... a travesty, and most significantly ... unconstitutional."
At a news conference on SB 1070, he said, "If I were a Hispanic person in the state, I would be humiliated and angered." He called the law "morally wrong."
Still, Dupnik said he would grudgingly enforce the law because it was his duty as sheriff to do so.
Not that the sheriff of a county that stretches 123 miles along the Mexican border is a softy on immigration. His 1,500-member department refers more illegal immigrants to the U.S. Border Patrol than any other law enforcement agency in Arizona.
He just wasn't keen on having his deputies spend all their time asking people for their papers.
Dupnik is an institution in Pima County. He has been sheriff for 30 years and has spent more than 50 years in Arizona law enforcement.
He was born in Texas and raised in the historic Arizona mining town of Bisbee near the Mexican border. Dupnik attended the University of Arizona in Tucson before graduating from Chicago's Keeler Institute, the nation's first polygraph, or "lie detector," school.
He joined the Tucson police department in 1958. In 1980, he was appointed sheriff and has been elected seven times since then.
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