After 38 years on the job, Minnesota's polite-but-fierce state government watchdog is stepping down to retire and devote more time to the beloved garden and unread books at his St. Paul home.

The best way to honor James Nobles' decades of dedicated service is by ensuring that the next legislative auditor shares the professional standards that were his hallmark. Among them: integrity, evenhanded scrutiny, stellar wordsmithing and attention to accuracy. And perhaps most importantly, a commitment to use this office's vast authority to improve state government, not pursue political ends.

These qualities never wavered over Nobles' long tenure and were shared by his hardworking staff of 65, a testament to his leadership. That feat is the bedrock on which the work of the Office of the Legislative Auditor (OLA) rests.

Without credibility, the program evaluations, special reviews and financial audits issued periodically would simply gather dust. It is the trust earned and maintained by the OLA that imbues its work with impact.

That reality must be foremost in legislators' minds as the work begins this fall to select Nobles' successor. His last day on the job is Oct. 5.

After nearly four decades, Nobles' name is nearly synonymous with his office. But the Arkansas native who will soon turn 74 isn't its only chief executive. A former Minnesota legislative staffer, Nobles first served as a deputy auditor, moving into the top job in 1983.

The OLA is an outgrowth of government accountability reforms by 1970s legislators. Minnesota also has a state auditor, currently Julie Blaha, who is elected and whose focus is local government.

The OLA's focus is state government. Legislators seek out its expertise when management, ethics or other questions arise about state affairs. Findings, reliably tough-minded but constructive, are public. They are read closely by policymakers and the press, and often spur legislative hearings and remedies.

Through the years, the OLA has weighed in on an array of troublesome controversies and concerns. It reviewed Metro Gang Strike Force abuses, MNsure launch struggles, state lottery leadership misconduct and fraud allegations in the state's child care assistance program, to name just a few.

A memorable moment came in 2003, when Nobles and his crew evaluated a dispute between then-DFL Attorney General Mike Hatch and the administration of then-GOP Gov. Tim Pawlenty, shedding needed light on questionable conduct on both sides.

The OLA also provided a valuable but painful public service in 2015 with its special review of a University of Minnesota drug trial. The report highlighted ethical concerns after U leadership had long batted away questions about the 2004 suicide of Dan Markingson, a patient enrolled in research.

Minnesota is one of about 27 states that has an OLA office. This week, Republican and DFL lawmakers lauded Nobles' leadership. "He is a fact-driven and principles-centered person," said Sen. Michelle Benson, R-Ham Lake. Rep. Rick Hansen, DFL-South St. Paul, called Nobles an "icon" and added that OLA reports aren't just the "gold standard" but the "platinum standard."

Nobles, in an interview, is appreciative of the praise. But he's also quick to say the OLA's work reflects the excellence of its staff, and that this will remain after he leaves. "This isn't the Office of James Nobles. It is the Office of the Legislative Auditor," he said.

To lawmakers who will select his successor, Nobles urged a "thorough review" to find someone who understands how vital is the office's independence and credibility. Good writing and editing skills are a must, too.

Minnesota is a better place because of Nobles' decades on the job. Lawmakers have a daunting task ahead to find a successor equally dedicated to making state government work better.