WASHINGTON — A fourth staff member has departed from the Department of Labor amid an extensive investigation by the department’s watchdog into Secretary Lori Chavez-DeRemer. The inquiry is centered around allegations of travel fraud and other forms of misconduct, according to information obtained by The Post.

Sources indicate that Melissa Robey, who held the position of director of advance within the secretary’s office, was dismissed on Tuesday following a recommendation from the White House. Her departure marks the latest in a series within the department, coinciding with an ongoing investigation by the inspector general.

Robey was placed on administrative leave on March 4 after accusations surfaced that she improperly used taxpayer money for travel purposes. This action came just one day after Chavez-DeRemer’s top aides resigned amid similar accusations.

Sources involved in the investigation report that sufficient evidence has been collected indicating a “toxic” workplace environment attributed to the pair. Allegations include verbal abuse towards staff and the misuse of departmental resources for personal travel needs.

Individuals familiar with the investigation also revealed that Robey was associated with excessive spending on travel-related activities.

Senior aides, including Chief of Staff Jihun Han and Deputy Rebecca Wright, are also implicated in creating a “hostile” work environment alongside Chavez-DeRemer, 57. They face allegations of “travel fraud,” including fabricating official trips to facilitate the secretary’s personal travel, funded by taxpayers.

Additionally, Brian Sloan, a bodyguard on the Cabinet official’s security detail, was sidelined on Jan. 16, following allegations of having an extramarital affair with Chavez-DeRemer. He resigned earlier this month.

Since January, Inspector General Anthony D’Esposito’s office has been probing allegations of misconduct — which were first exposed by The Post — that also claimed the labor secretary was abusing her position and even drinking in her office during the workday.

Sen. Chuck Grassley (R-Iowa), who chairs the Judiciary Committee, has also demanded information about the alleged sexual and workplace misconduct — including evidence that the secretary allegedly took subordinates to an Oregon strip club shortly after she was confirmed by the Senate in April 2025.

The White House has stood by the secretary throughout the investigation, with President Trump frequently congratulating Chavez-DeRemer for her work at DOL in public events.

Han and Wright had worked for her in the House when she served as a House Republican representing Oregon’s 5th Congressional District from 2023 to 2025.

The Treasury Department had to pay out nearly $100,000 in taxpayer-appropriated funding last year to settle an employment discrimination claim stemming from Chavez-DeRemer’s congressional office — the highest sum recorded since 2019.

“It is the policy of the Department of Labor not to comment on personnel matters,” a DOL spokesperson said.

Robey and the White House did not immediately respond to requests for comment.