Senate veteran William D. Duhnke III will return to his old job as minority staff director of the Senate Appropriations Committee, the panel’s top Republican confirmed.

Sen. Richard C. Shelby, R-Ala., called Duhnke, a longtime aide, a “highly qualified and trustworthy” person. “He knows the process. He’s worked in approps. He knows it all,” Shelby said Thursday.

Duhnke returned to the Appropriations staff as general counsel last year after Securities and Exchange Commission Chairman Gary Gensler — a Democrat who had recently assumed the top SEC job — removed Duhnke from his position as chairman of the Public Company Accounting Oversight Board. The move was part of a broader PCAOB overhaul Gensler orchestrated, including removal of other board members who served during the Trump administration.

Duhnke served as Appropriations Committee minority staff director in the 113th Congress when Shelby was the panel’s ranking Republican, among other majority staff director and general counsel positions on other committees during a 20-year career in the Senate.

Shelby has announced he will retire when the 117th Congress ends in January 2023. His current staff director, Shannon Hines, is headed to a defense-related firm when she leaves the Senate next month, according to sources familiar with the move who spoke on condition of anonymity.

In a tribute to Duhnke after he was appointed to the PCAOB in December 2017, Shelby said when he hired him as an aide in 1995, Duhnke “quickly revealed his high work ethic and innate ability to thrive when tasked with the most challenging of assignments.”

Shelby said the Wisconsin native “brought a high level of respect and discipline to the workplace” and “was able to spearhead tasks and get things done.”

Duhnke’s three and a half years as chairman of the PCAOB, which regulates the audits of publicly traded companies, were marked by controversy and whistleblower complaints.

The Wall Street Journal reported last year that Duhnke “sought to overhaul its largely outdated quality-control rules and streamline how it conducts inspections of audit firms.” The Journal also said the SEC, which oversees the agency, was investigating whether Duhnke violated any rules in his handling of internal complaints.

Duhnke said in a written statement at the time that “every single allegation of wrongdoing that has been made against me is false” and that individuals orchestrated “a well-coordinated smear campaign” against him.

The SEC declined to respond immediately to a request about whether Duhnke is under investigation by the agency. A source familiar with the situation, who spoke on condition of anonymity because of the matter’s sensitivity, said the investigation was closed without turning up evidence of wrongdoing.

Shelby appeared to accept there would likely be criticism if he brought Duhnke back as his top aide, but that it wouldn’t dissuade him. “He had a big fight; it’s politics, you know,” Shelby said.

Blair Taylor, Shelby’s communications director, added that her boss “has complete confidence in Bill Duhnke as the next staff director.”

Duhnke worked for Shelby as majority staff director and general counsel to the Senate Rules and Administration Committee prior to his move to the PCAOB in January 2018. He earlier served two stints as majority staff director and general counsel to the Senate Banking, Housing and Urban Affairs Committee, and before that as majority staff director and general counsel of the Senate Select Committee on Intelligence, both under Shelby.

A graduate of the University of Wisconsin-Madison, he served in the Navy from 1984 to 1991. After leaving the Navy, he worked on the staff of the Presidential Commission on the Assignment of Women in the Armed Forces and the Defense Base Closure and Realignment Commission.

Duhnke has a law degree from Catholic University.