After less than three months on the job, the internal watchdog of the State Department has resigned, U.S. officials said, marking another significant shake-up for an office sworn to investigate malfeasance and wrongdoing.

Stephen Akard’s departure was announced to staff by his deputy, Diana R. Shaw, who told colleagues that she will become the temporary acting inspector general effective on Friday.

Akard became inspector general after President Trump abruptly fired Steve Linick in May at the recommendation of Secretary of State Mike Pompeo. That decision immediately prompted criticism from lawmakers because Linick had been investigating allegations that Pompeo and his wife, Susan, had improperly used State Department resources. Linick was also examining several other issues, including Pompeo’s decision to expedite arms sales to Saudi Arabia over the objections of Congress.

Trump and his administration have come under increasing criticism for trying to evade oversight because the president has fired five officials in recent months who lead inspector general offices across the federal government.

In a note to her inspector general’s office colleagues that was obtained by The Washington Post, Shaw said Akard was taking a position with a law firm in Indiana, his home state. It’s unclear whether there were other factors in his decision.

Pompeo dismissed a question about Akard’s departure during a news conference on Wednesday. “He left to go back home,” Pompeo said. “This happens. I don’t have anything more to add to that.”

Akard’s resignation again throws into turmoil an office responsible for ongoing investigations into wrongdoing at the department, including those started by Linick. Shaw told colleagues: “I will do my best not to let this latest change negatively affect our operations.”

Akard had been under consistent pressure from Democratic lawmakers since his appointment. He is an ally of Vice President Pence, for whom he worked as the head of the Indiana Economic Development Corp. That connection to Pence and his decision to keep his title as head of the State Department Office of Foreign Missions, a position that comes under the oversight responsibilities of the inspector general, drew criticism from good-government experts.

In recent days, Akard promised to recuse himself from ongoing investigations of Pompeo and his wife after congressional Democrats questioned whether Pompeo pushed for Linick’s ouster to bury the investigations. Pompeo has denied those allegations and said he didn’t know about the content of Linick’s investigations except for the one involving arms sales to Saudi Arabia.

Pompeo called Linick a “bad actor” and said he refused to advance the interests of the secretary and the State Department. Critics have pointed out that the inspector general is designed to be independent of the secretary and often plays an adversarial role to shed light on problems in the department.

On Monday, senior Democratic lawmakers in Congress continued their investigation into the reason behind Linick’s firing, issuing subpoenas for the depositions of four senior U.S. officials: Undersecretary for Management Brian Bulatao; Deputy Assistant Secretary of State for Political-Military Affairs Michael Miller; acting legal adviser Marik String; and senior adviser Toni Porter.

On Wednesday, the top Democrat on the Senate Foreign Relations Committee, Sen. Robert Menendez of New Jersey, said Akard was not the “right choice to lead the office, but I am concerned that his sudden resignation leaves another opportunity for the Trump administration to try to weaken oversight and accountability.”

He added that the Democrats’ investigation into Linick’s firing “will continue full speed ahead.”

In June, Linick told lawmakers in a video interview that he doesn’t think there is “any valid reason” that would justify his firing. He has said he was investigating five matters of wrongdoing at State, which included the probes into arms sales and inappropriate use of department resources.

Carol Morello contributed to this report.