NASHVILLE (AP) — Federal prosecutors said this week they intend to file a lawsuit against a Tennessee state senator and other co-owners of a now-shuttered pain clinic company.

Court filings said Comprehensive Pain Specialists, which was based in Tennessee and once operated in 12 states, defrauded the government of millions of dollars by submitting claims for unnecessary procedures and falsifying documents.

On Wednesday, U.S. District Judge Aleta Trauger granted federal and state prosecutors' notices of intention to intervene in whistleblower complaints against the company. They have 90 days to file their own complaints.

U.S. attorneys also notified the court that they are adding Tennessee Sen. Steve Dickerson, among other defendants. The Nashville Republican and anesthesiologist declined to comment on Thursday.

The whistleblower complaints include one by Dr. Suzanne Alt, who worked at CPS clinics in Missouri and Iowa in 2014 and 2015.

Alt said in her complaint that she was personally instructed to increase the number of full-panel drug screenings she was performing, all of which were sent to a CPS-owned lab in Tennessee for processing.

When she questioned why she could not perform an alternative, cheaper test done in the clinic, she was told to do it "the CPS way," according to the complaint and was later fired.

Alt's complaint also alleges that physicians received a percentage of the laboratory revenue, in violation of the Stark Act, which prohibits physicians from making referrals in which they have a financial interest.

Two former CPS office workers, Mary Butner and Dana Brown allege in their complaint they were instructed to cut and paste forged signatures to documents in order to obtain pre-authorizations for treatments. They were also told to falsify patient records to make them appear eligible for services. They also said they were fired for questioning the company's actions.

Former compliance director Jennifer Pressotto alleges in her complaint that CPS employees treated patients with an acupuncture device that was not eligible for reimbursement but billed for a totally different treatment. When Pressotto demanded the company reimburse Medicare and Medicaid, she was fired, according to the complaint.

A complaint from physician's assistant Allison Chancellor alleges CPS ordered unnecessary genetic and psychological tests along with the drug screens.

Her complaint points to a clinic in Illinois that was purchased by CPS. Before the purchase, drug screening accounted for less than 1% of a clinic doctor's Medicare billing, or about $2,000 in 2013. In 2014, after CPS took over, that same doctor's billing for drug screens amounted to 42% of his Medicare billing, or $246,000.

Her complaint states she was told to order the drug screen at every Medicare patient visit and that "Medicare patients were less likely to question the urine drug screens because they were unlikely to review the claims."

Like the others, Chancellor said she was fired when she complained about the company's practices.

CPS clinics closed suddenly last summer, shortly after former CEO John Davis was indicted in a criminal complaint. He was found guilty earlier this month of receiving kickbacks in relation to a federal health care program and federal prosecutors say he will be a defendant in their complaint.

An attorney who has represented CPS as an interested party in the criminal case against Davis did not immediately respond to phone and email messages.