Debra S. Ritt, the Smithsonian Institution's inspector general, resigned last week to take a senior executive position at the Small Business Administration, in part because she feared that shrinking resources for her Smithsonian office would lessen its effectiveness and independence.

"In the last 10 years, the number of positions in this office went down 30 percent while the federal appropriation has grown 70 percent," Ritt said yesterday in a phone interview.

As the Smithsonian expands its undertakings with new museums and new moneymaking ventures, Ritt said, the office's responsibilities should increase. "The more there is of the Smithsonian, the more oversight from the inspector general is needed," she said.

Current inquiries include an audit of executive compensation at the Smithsonian and the accounting practices and salaries at Smithsonian Business Ventures, the division of the museum that runs its profit-making enterprises.

The Business Ventures unit has drawn fire from filmmakers, historians and members of Congress, who charge that the near-exclusive agreement it negotiated with Showtime Networks for television programming will limit access to museum resources.

In its latest report, the inspector general's office points out that it also questioned $340,000 in annual bank fees that the Smithsonian paid. Another discovery: A diversion of funds through a false change of address so that $107,000 went to a person who was not supposed to receive it.

In recent years, the inspector general's office was also involved in checking allegations of animal mistreatment at the National Zoo, which is part of the Smithsonian.

The inspector general conducts audits and investigations to prevent and detect wrongdoing at the institution. The office issues a semiannual report to Congress and Smithsonian Secretary Lawrence M. Small.

In a short note to the staff announcing Ritt's departure, Sheila P. Burke, the deputy secretary and chief operating officer, said, "I know the Smithsonian community joins me in wishing Debra every success in her new position and thanking her for her service to the Institution."

Ritt, 52, said she would like to see the inspector general answer directly to the Board of Regents, the 17-member body that governs the Smithsonian. Now she reports to the secretary. "The IG should be hired by the regents and report to the regents. We should be an independent assessment group," she said.

She said she was apprehensive that an interim IG would be compromised if that person came from inside the Smithsonian. "My fear is that they will bring in someone they can control. We are doing some things that are controversial," Ritt said. Since the Smithsonian established the office in 1989, the two IGs have been recruited from outside the Smithsonian.

In addition, she said she had broadened the SBV audit to look at executive compensation throughout the Smithsonian and do a more detailed examination of the revenues and financial impact of SBV. The office is "going to take a hard look at the accounting practices, especially when they are so different from the rest of the Smithsonian," Ritt said.

Budgets for most departments at the Smithsonian are tight. Although congressional appropriations have increased in the past decade, Congress has directed that most of the additional money be spent on repairs to the crumbling buildings, not expansion of the paid staff.

A government auditor for more than 30 years, including 23 at the Government Accountability Office, Ritt took a pay cut to join the Smithsonian in 2005. She said family considerations played a part in her decision to move to the SBA post, which pays more. Her husband is retired and the youngest of her three sons is heading to college this fall.