By Gregory Wallace, CNN

(CNN) -- In the Trump era, the sometimes-obscure role of inspector general is taking a turn in the spotlight.

From Democrats on Capitol Hill to good-government groups, critics of President Donald Trump and his administration have turned to the federal government's 70-plus inspectors general seeking answers.

The requests for IG investigations vary as widely as the headlines: The government's handling of Trump's Washington hotel. The President's firing of former FBI Director James Comey. Cabinet secretaries' use of charter airplanes. The reassignment of an Interior Department scientist to an accounting position.

A report last week by the Environmental Protection Agency's inspector general said its investigations into potential employee fraud "have been on the rise because of recent attention from Congress and because of the attention garnered from our investigative successes being publicized in the media."

Walter Shaub, a former top ethics official who's now a CNN contributor, said he sees "an increased volume of interest and referrals" to the IGs.

"I think IGs have always felt they live a bit in a fishbowl," said Shaub, who as director of the Office of Government Ethics was a member of the government's Council of the Inspectors General on Integrity and Efficiency. "IGs always get a lot of scrutiny, and those who are not in power in Congress feel they have to turn to the IGs because they don't have the power of a committee chair."

Some Democratic members of Congress have been particularly vocal as their requests for information from the administration have gone unanswered.

"To date my colleagues and I have sent more than 40 letters to the Trump administration asking for information necessary to carry out our oversight responsibilities," Rep. John Conyers of Michigan, the top Democrat on the House judiciary committee, said Tuesday. "To date, we have not received a single substantive response."

Liz Hempowicz, public policy director at the nonprofit Project On Government Oversight, agreed the inspectors general are in the spotlight more.

"I'm not sure if there is an increased attention on IGs because of Trump" or because in the wake of a decline of trust in government in general, "an individual is more likely to look at the watchdogs," she said.

Wary of wading into politics, spokespeople for several inspector general offices declined to comment or did not respond to questions for this report. Inspectors general rarely speak in public, preferring for their audits and reports to represent their work. In some cases, such as employee misconduct, IGs disclose little or nothing about their conclusions.

But several inspectors general will speak publicly on Wednesday morning when they answer questions from the House Committee on Oversight and Government Reform.

IGs from the Department of Homeland Security, the Department of Justice and the Peace Corps are scheduled to testify. The latter two hold leadership positions on the Council of the Inspectors General on Integrity and Efficiency.

When several of the same inspectors general appeared before the committee in February, their work was praised by both sides of the aisle.

Then-Chairman Jason Chaffetz, a Utah Republican who has since retired and is now a Fox News contributor, asked the IGs and their staff members who were present to stand. "Thank you, thank you, thank you on behalf of all of us who serve here," he told them.

Rep. Elijah Cummings of Maryland, the top Democrat on the committee, said at the February hearing that the importance of the position is underscored by the "many employees who are now going to inspector generals because they're afraid."

"So your jobs become very, very, very significant -- even more significant than they've ever been because people see you as the last line of defense," Cummings said.

More than 13,000 people work for the more than 70 inspectors general, according to a report from the Council of the Inspectors General on Integrity and Efficiency.

Their offices released more than 2,200 reports in the most recent fiscal year, including more than 8,800 recommendations to reduce government waste, fraud, abuse and mismanagement.

There's a return on that investment in the form of cost savings, the council has said. A 2012 report found that IGs identified potential savings of $17 for every $1 spent on their offices.