Another high-level aide to Environmental Protection Agency chief Scott Pruitt is leaving the agency this week, as federal investigators continue to scrutinize the administrator’s spending and management decisions.

Liz Bowman, the agency’s top spokesman, is stepping down to become communications director for Sen. Joni Ernst (R-Iowa).

Her departure follows the exit of two other top Pruitt aides this week. Albert “Kell” Kelly, who was Pruitt’s banker in Oklahoma and hired to revitalize the agency’s Superfund program cleaning up toxic sites nationwide, resigned Tuesday. So did Pasquale “Nino” Perrotta, the head of Pruitt’s personal security team who has come under congressional scrutiny recently for unusual spending on Pruitt’s protective detail.

Other senior EPA officials also could leave in the coming weeks, according to two individuals who spoke on the condition of anonymity to discuss personnel matters.

“I leave extremely thankful for the opportunity to serve the Trump Administration and Administrator Pruitt,” Bowman wrote in a statement.

Bowman also praised EPA career staff in her departing statement. “Being a member of the EPA team has allowed me to further my skills, learn from my mistakes, and make lifelong friendships. It has also provided me the opportunity to develop a new, and deep, respect for the public servants who serve the American people, day in and day out, to ensure that we all have access to clean air, land, and water.”

Under Bowman, the EPA’s press shop aggressively defended Pruitt’s work, often in news releases calling out media outlets and reporters whose coverage the agency said was misleading or inaccurate.

After Hurricane Harvey hit Houston last year, the agency’s press office charged a D.C.-based journalist at the Associated Press with “reporting from the comfort of Washington,” even though other AP reporters co-wrote the stories from Houston. The AP had reported on the flooding of toxic Superfund sites in the hurricane-hit city that EPA employees had not yet been physically able to visit.

In a statement at the time, Bowman accused the news wire service of “cherry-picking facts” and of practicing “yellow journalism.”

“What Liz brought to the table at EPA was good judgment, good management, good organization,” EPA chief of staff Ryan Jackson said in a statement. “She has a great opportunity ahead of her at the Senate. She will work for a great member that has a great future in front of her.”

Before working at the EPA, Bowman directed communications at the American Chemistry Council, the lobbying arm in Washington of the chemicals industry. Her last day at the EPA will be May 11.

The EPA’s press shop has seen a noted degree of turnover apart from Bowman, with Amy Graham and J.P. Freire leaving their roles as spokespeople for Pruitt’s EPA after less than a year on the job each.

Two EPA officials said Thursday that Bowman sought to remove herself from the push to challenge reporting by multiple media outlets about allegations of ethical misconduct by Pruitt, instead leaving that task to spokesman Jahan Wilcox.

Perrotta and Kelly, the other two Pruitt aides who announced their departures in recent days, have become flash points of controversy within the EPA.

Perrotta was scheduled to be interviewed by investigators at the House Oversight and Government Reform Committee this week to explain his role in adding personnel to Pruitt’s security detail as lawmakers question whether the EPA is spending too much money on the administrator’s security.

Democratic lawmakers are also worried about a $125,000 fine Kelly received from the Federal Deposit Insurance Corporation, which later banned him from banking industry altogether.

The FDIC had found reason to believe Kelly “violated a law or regulation, by entering into an agreement pertaining to a loan” without the agency’s approval, according to a consent agreement that Kelly signed in May 2017 and that E&E News obtained. In the agreement, Kelly did not admit or deny wrongdoing.