A state lawmaker in Missouri was charged this week in connection with a fraud scheme in which she claimed she could use stem cells to treat Covid-19 patients at her medical clinics, prosecutors said.

The lawmaker, Representative Tricia Derges, a Republican, was stripped of her committee assignments in the State House on Monday, the same day that a 20-count indictment against her was unsealed in U.S. District Court in Springfield, Mo.

And on Wednesday the House speaker in Missouri, also a Republican, urged the beleaguered first-term lawmaker, who has pleaded not guilty, to step down.

Prosecutors say that Dr. Derges, a licensed assistant physician, raked in nearly $200,000 from patients at three medical clinics that she operates for injections of amniotic fluid that she falsely claimed contained stem cells.

A month after the coronavirus outbreak was declared a global pandemic, Dr. Derges claimed in a Facebook post that the injections could help patients with symptoms of Covid-19, the illness caused by the virus, according to the indictment.

“This amazing treatment stands to provide a potential cure for COVID-19 patients that is safe and natural,” the indictment said Dr. Derges wrote in the post. “All of the components of the God given amniotic fluid: Mesenchymal Stem Cells (progenitor stem cells which are baby stem cells: can become any tissue they want); cytokines, exosomes, chemokines, hyaluronic acid, growth factors and over 800 proteins working to create a human being: the emphasis on the lungs.”

The National Institutes of Health last year recommended against the use of mesenchymal stem cells for the treatment of Covid-19, except in clinical trials. They also noted that the Food and Drug Administration had issued several warnings that patients could be vulnerable to stem cell treatments that are illegal and potentially harmful.

According to her biography on her legislative website, the clinics operated by Dr. Derges are primary and urgent care centers for the “working person and non-insured” in underserved areas of southwest Missouri.

The fraud scheme began in December 2018 and continued until May 2020, according to the indictment, which stated that Dr. Derges had promoted the regenerative medical benefits of the injections for treating chronic obstructive pulmonary disease, Lyme disease, erectile dysfunction, urinary incontinence and other conditions.

“This defendant abused her privileged position to enrich herself through deception,” Tim Garrison, the U.S. attorney for the Western District of Missouri, said in a statement. “As an elected official and a health care provider, she deserves to be held to a high standard.”

Dr. Derges, 63, of Nixa, Mo., was also charged with illegally providing the prescription drugs oxycodone and Adderall to clients of her three medical clinics in the Ozarks in southwestern Missouri, along with lying to federal investigators.

Stacie Calhoun Bilyeu, a lawyer for Dr. Derges, said in an interview on Wednesday night that the public was rushing to convict her client before she gets her day in court.

“My client began getting death threats,” Ms. Bilyeu said. “Somebody told her that they hoped she died by lethal injection.”

Ms. Bilyeu declined to discuss details of the case, including the government’s allegations that Dr. Derges had charged patients as much as six times more than what she paid for amniotic fluid allograft that did not contain stem cells.

Dr. Derges obtained a medical degree from Caribbean Medical University in Curacao in 2014 but was not accepted into a postgraduate residency program, according to the indictment. In 2017, she became a licensed assistant physician in Missouri and became authorized to prescribe medications the following year, the indictment said.

Prosecutors said that Dr. Derges had illegally provided prescription drugs to patients of other practitioners at her clinics who were not authorized to prescribe controlled substances.

On Monday, Dr. Derges, who was elected to her first two-year term in 2020, was stripped of her assignments on the Health and Mental Health Policy Committee, along with the Professional Registration and Licensing Committee and the Special Committee on Small Business.

She was removed at the behest of Representative Rob Vescovo, the speaker of the Missouri House and a fellow Republican.

“After speaking with her and with the caucus, I am asking her to resign her seat with the House,” Mr. Vescovo said in a statement on Wednesday. “The legal process will ultimately determine her guilt or innocence, but this is clearly a time for her to spend with her family as she focuses on her legal issues, and for the people of the 140th District to move forward with selecting a replacement who can effectively advocate for their interests.”