Congressional leaders want to investigate claims of sexual misconduct in the U.S. Forest Service in the wake of the agency chief's abrupt resignation on Wednesday.

Agriculture Secretary Sonny Perdue said he'd accepted Chief Tony Tooke's resignation on Wednesday evening, after Tooke acknowledged that his own behavior was under investigation as the agency deals with sexual harassment and abuse incidents.

On Thursday, saying that "it has been a difficult week in the Forest Service," Perdue announced the appointment of Vicki Christiansen as interim replacement chief. She was serving as deputy chief of State and Private Forestry in the agency's Washington, D.C. headquarters.

Christiansen served as interim regional forester for Region 1, based in Missoula, in 2012. She did not return an emailed message from The Associated Press seeking comment.

A relative newcomer to the Forest Service, Christiansen was the state forester in Arizona and Washington before moving to the federal government in 2010. She has 30 years of experience as a wildland firefighter and fire manager with special expertise as a fire line blasting adviser.

Before coming to Missoula, Christiansen was the deputy director of fire and aviation management in the Forest Service in Washington, D.C. She helped develop the National Cohesive Wildland Fire Management Strategy. 

Congressional leaders also called for scrutiny into the sexual harassment and misconduct incidents at the Forest Service. Sen. Steve Daines, R-Montana, pledged to hold hearings on the allegations.

“I am distraught and angered that this happened in Montanans’ own backyard," Daines wrote in an email on Thursday. “Strong leaders are needed to change the culture of the organization and I believe Mr. Tooke’s resignation was the right decision. I plan to use every tool to ensure all bad actors are held accountable.”

Rep. Jackie Speier, D-California, called for a broad investigation of the Forest Service's "toxic culture" by the Inspector General of the U.S. Department of Agriculture, according to the Associated Press. 

Tooke became head of the Forest Service last August, replacing Tom Tidwell as the leader of almost 30,000 employees in all 50 states. An expose last week on PBS aired accounts of numerous female Forest Service employees, including firefighters in Montana, recounting a culture of harassment in the agency. It included a report that Tooke was under investigation following relationships with subordinates prior to his appointment last August.

Preliminary results of a sexual harassment audit released Thursday by the Agriculture Department's inspector general said that almost half of employees interviewed had expressed distrust in the process of reporting complaints.

Perdue said more steps already were being taken to protect victims from retaliation. Those include using outside investigators for at least the next year to investigate sexual misconduct complaints, according to the Agriculture Department inspector general's audit released Thursday.

Representatives of the Forest Service and its parent agency, the Department of Agriculture, did not answer repeated questions Thursday about whether the investigation into Tooke would continue. They also declined to answer if an outside investigator was handling the case.

In his resignation letter, Tooke acknowledged that he was part of the problem.

“In some of these news reports, you may have seen references to my own behavior in the past,” Tooke wrote in an email to Forest Service employees. He wrote that, "I cannot combat every inaccuracy that is reported in the news media."

"What I can control, however, are decisions I make today and the choice of a path for the future that is best for our employees, the Forest Service and the U.S. Department of Agriculture. I must also think about what is best for my family. Therefore, I have decided that what is needed right now is for me to step down as Forest Service Chief and make way for a new leader that can ensure future success for all employees and the agency.”

Tooke said his retirement was effective immediately. 

In the two-part report by PBS NewsHour last week, the Forest Service acknowledged that it had received 1,013 reports of harassment, and completed inquiries or investigations in 632 cases since September 2016. 

Abby Bolt, a Forest Service employee in California with a pending sexual discrimination complaint against her male supervisors, told The Associated Press that rumors of Tooke's relationships had started circulating within the agency as soon as he was appointed.

Bolt, a fire battalion chief now on leave, said she was hopeful Christiansen would bring some "fresh eyes" to the Forest Service's problems, but also wants Tooke held to account for any wrongdoing.

"If we just have somebody retire and step down, then we don't get to see that," Bolt said.

The Forest Service oversees 154 national forests and 20 grasslands in 43 states and Puerto Rico.