The top executive of a large Twin Cities mental health agency, under investigation for defrauding the state Medicaid program of millions of dollars, has been ordered by state regulators to cease practicing as a social worker.

Teri Dimond, the president of Complementary Support Services (CSS), has agreed to a cease-and-desist order from the Minnesota Board of Social Work until the board completes a probe of allegations against her, according to a stipulation signed by her and the board.

The cease-and-desist order is the latest blow for CSS, a community-based mental health agency that faces allegations from federal and state prosecutors that it knowingly bilked the state Medicaid program and failed to adequately supervise its unlicensed practitioners. A recent Star Tribune story quoted former and current employees of CSS describing an agency that put patients’ mental health at risk by violating state rules on clinical supervision and record-keeping.

Dimond did not return calls seeking comment. A person answering calls Wednesday at the agency’s Richfield office said the nonprofit was still providing services.

At its peak, CSS had an expansive network of 80 mental health practitioners that provided counseling and other services to children and adults in 16 counties across the Twin Cities and outstate Minnesota.

Last November, federal prosecutors and Minnesota Attorney General Lori Swanson accused the agency of billing the state Medicaid program for hundreds of patients without providing adequate supervision by licensed professionals, as well as padding claims with extra hours.

Rather than personally reviewing claims for patient care, Dimond “batch signed” thousands of documents, known as progress notes, that formed the basis of the agency’s claims to Medicaid, according to a civil complaint. Prosecutors allege the fraud began as early as 2007 and cost taxpayers millions of dollars.

A federal judge has ordered representatives of CSS and prosecutors to a settlement conference on May 23 in St. Paul.

The case highlights a long-standing gap in Minnesota’s oversight of mental health services. Like roughly 200 other community-based agencies, CSS is unlicensed and not subject to routine regulatory oversight Despite the recent allegations, CSS is still certified by the Minnesota Department of Human Services (DHS) to bill Medicaid for adult mental health services. However, the agency has voluntarily suspended its certification to bill Medicaid for therapeutic support services to children, according to DHS.

The Board of Social Work is an independent state agency that licenses about 14,200 social workers and is charged with ensuring they meet minimum professional standards for care. The board issued six cease-and-desist orders against licensed social workers in 2015.