A high-ranking federal prosecutor in Washington stepped down on Tuesday, stating that officials appointed by President Trump had pressured her to initiate a criminal investigation into a government contract awarded during President Biden’s administration, which she deemed inappropriate.

Denise Cheung, who oversaw criminal cases at the U.S. Attorney’s Office in Washington, disclosed that she had been instructed to start an investigation into an undisclosed contract. She expressed her belief that the request lacked substantiated evidence in a letter assessed by Reuters.

Upon refusing to commence a grand jury investigation due to the absence of proof, Cheung recounted being directed to pursue confiscating assets to prevent the contract recipient from accessing government funds.

“I have been proud to serve at the U.S. Department of Justice and this office for over 24 years,” Cheung wrote in the letter to interim U.S. Attorney Ed Martin. “During my tenure, which has spanned over many different administrations, I have always been guided by the oath I took …to support and defend the Constitution.”

Spokespeople for the U.S. Attorney’s office and the Justice Department did not immediately respond to a request for comment.

Her resignation is the latest by career Justice Department prosecutors to protest what they see as improper political interference by the Trump administration in criminal investigations.

Dozens of career Justice Department officials — who normally remain in office from one administration to the next — in cities including Washington and New York have been fired or quit since Trump took office on January 20, vowing to rapidly shake up a department that he says was used against him during his years out of power.

Roughly 20 prosecutors who investigated Trump supporters who stormed the U.S. Capitol on January 6, 2021, have been reassigned.

The Trump administration has sought to freeze government funding, fire civil servants and shutter federal agencies including the U.S. Agency for International Development, which was tasked with providing humanitarian aid throughout the world.

Cheung said in her letter that at first, she was ordered to launch a grand jury investigation into whether the contract was unlawfully awarded during the Biden administration.

But after reviewing documentation provided by the Deputy Attorney General’s office, she said that she and her colleagues determined that there was not sufficient evidence to justify a grand jury probe into crimes including wire fraud and conspiracy to defraud the United States.

After she rebuffed the request for a criminal probe, Trump administration officials changed course and ordered her to pursue an asset freeze.

Cheung said she consulted with officials in the FBI Washington field office.

Ultimately, she said, they decided to send the bank a letter “recommending a 30-day administrative freeze on certain assets.”

After the letter was sent, she said Martin and the No. 2 official in the office called her Monday night to say the letter was not adequate, and they ordered her to immediately send a second letter to the bank demanding it freeze the assets as part of a criminal investigation.

“When I explained that the quantum of evidence did not support that action, you stated that you believed that there was sufficient evidence,” she wrote.

“Based upon the evidence I have reviewed, I still do not believe there is sufficient evidence to issue the letter you described, including sufficient evidence to tell the bank there is probable cause to seize the particular accounts identified.”

Cheung said in her letter she was ordered to resign. She announced her departure early Tuesday.