When the Minnesota health exchange disclosed the Social Security numbers of about 1,500 insurance agents in September, MNsure's director blamed the data security breach on one worker's mistake.

But after a two-month investigation, the Legislature's watchdog office concluded MNsure's administrators also had botched the handling of that private information.

"It was others at MNsure, not the employee, who made the decision to collect Social Security numbers from brokers," the Office of Legislative Auditor said in a report last week.

"It was others, not the employee, who allowed Social Security numbers -- as well as other personal data -- to be transmitted by unsecured email when more secure methods were available. It was others, not the employee, who allocated few staff to the development of a broker training and certification process."

Legislative Auditor Jim Nobles said he issued that hard-hitting report to make sure MNsure managers recognized their fingerprints were on the data blunder.

"An agency that is in the glare of that kind of scandal is inclined to say, 'It was just a bad apple, a rogue employee,' " he said. "But those breakdowns are always shared responsibility between the individual and the organization."

That's the kind of pull-no-punches analysis that state lawmakers and Capitol observers have come to expect from Nobles.

For 30 years, whenever there has been a hint of graft, waste or mismanagement in state government, policymakers have almost always turned to Nobles and his staff to investigate it.

In recognition of his work, the Legislative Audit Commission -- the panel of lawmakers that oversees the watchdog office -- voted unanimously Friday to reappoint Nobles, 66, to his sixth six-year term as auditor.

"I don't know that I've worked with anyone at the Capitol who is as thoughtful, measured and objective as Jim," commission chairman Sen. Roger Reinert, DFL-Duluth, said before the vote.

The commission's Republican vice chairman, Rep. Mike Beard of Shakopee, called Nobles a nonpartisan straight shooter.

"His team is respectful, thorough and fearless," Beard said.

Nobles heads a staff of 60 accountants, investigators and policy analysts. Their main job is to conduct financial audits of state agencies and produce detailed "thick books that nobody understands," he said, but credit rating agencies require.

What gets headlines, however, are the handful of investigations that turn up corruption in agencies, theft by employees, flawed policies and wasteful spending.

A 2009 audit led to shutting down the Metro Gang Strike Force for financial mismanagement.

Twenty years earlier, an investigation into a kitchen remodeling project at East-cliff, the University of Minnesota president's residence, prompted President Ken Keller to resign.

Two years ago, an audit called attention to legal questions about the state's authority to lock up indefinitely civilly committed sex offenders who already served prison sentences. That program is now the subject of a federal lawsuit and the source of a heated political debate at the Capitol.

Nobles doesn't go looking for headline-generating investigations. But they keep popping up as his staff sorts through the management of state-funded programs. (State Auditor Rebecca Otto's staff is responsible for auditing local governments.)

"Our mission is to strengthen legislative oversight and accountability in state government," Nobles said.

He was born and raised in Hot Springs, Ark., earned a bachelor's degree at Brigham Young University and a graduate degree in public administration from the University of Minnesota.

He went to work at the Legislature as an intern in 1972 and never left. He worked in the nonpartisan House Research Department before being appointed deputy legislative auditor in 1981 and moving up to the office's top post two years later.

While not a native Minnesotan, he has deep roots in the state. His great-great-grandfather, William H. Nobles, moved here from New York in the 1840s to open a lumber mill on the St. Croix River and served in the territorial legislature in the 1850s.

Nobles said he's been interested in government since he was in high school but never was inclined to run for elected office.

"This is an ideal situation for me to have a significant impact on government through the work of this office without being directly involved in politics," he said.

But he's not nave. He's learned how to maneuver through highly charged political dramas without being partisan.

Asked to reflect on some of his office's most consequential cases, he said the Metro Gang Strike scandal was the most outrageous.

The strike force was made up of cops and sheriff's deputies from throughout the Twin Cities area organized to combat gang crimes across city and county boundaries. But in 2009, state Public Safety Commissioner Michael Campion suspected the operation was running amok and asked Nobles to investigate.

He and an auditor went to the strike force's evidence room and found it filled with television sets, stereo equipment, jewelry and hundreds of thousands of dollars in cash in a safe.

"We walked into the room with a bunch of guys with guns staring us down, like 'Who the hell are you?' It was pretty tense," he recalled.

What they found was a "police operation completely out of control," he said. Cops were shaking people down, and cars and other items they confiscated were missing and couldn't be located.

"It royally irritated me that cops were abusing their authority," he said. "It was going to be another story that gives cops a bad name. I don't like that, but I don't like what they were doing."

He was even angrier that some high-ranking law enforcement officers had let it get out of control and then tried to dismiss his report. Campion didn't; he quickly shuttered the operation.

The Eastcliff audit started out as a review of extravagant spending on a kitchen remodeling project but soon evolved into a broader examination of how the university constructed and maintained buildings, much of it financed with money from what some characterized as a "slush fund" outside the purview of the board of regents. It led to President Keller's resignation.

The investigation with the most tragic ending, Nobles said, was a 2004 audit that found lottery director, George Andersen, had made some questionable deals with lottery promoters. The day after Nobles briefed the director on their findings, Andersen committed suicide.

"It was a tough, critical report," Nobles said. "I told George there were causes for concern, but nothing that would get him indicted."

Andersen's suicide is still a mystery to him.

Some of the most important evaluations aren't dramatic or criminal, he said, but they make governors and lawmakers rethink their policies "because we have sometimes told ourselves things that are not true."

In the 1980s, Gov. Rudy Perpich nicknamed Minnesota the "brainpower state -- and we believed it," Nobles said.

But in 1988, his staff questioned whether the state could legitimately claim that title, in part because it had no high school graduation standards. They produced a report that found kids could graduate without passing any statewide tests or meeting any state course requirements. That report prompted policymakers to set student performance yardsticks.

"The standards are still an ongoing issue," Nobles said, "but the report caused policymakers to think more honestly about what we are accomplishing in that area."

Nobles could retire, but he said he still has a lot of work to do and the physical and mental capacity to do it.

"Winston Churchill said, 'If you find a job you love, you'll never work again,'" he said. "Some days do feel like work, but I do love this job. It is not easy, but it is satisfying."