The Department of Justice (DOJ) on Monday announced its intervention in a lawsuit alleging retail pharmacy chain Rite Aid filled hundreds of thousands of prescriptions for medically unnecessary oxycodone and other opioids in violation of multiple federal laws.

The agency’s complaint, filed in U.S. District Court for the Northern District of Ohio, alleges from at least May 2014 through June 2019, Rite Aid pharmacists “filled at least hundreds of thousands of unlawful prescriptions for controlled substances that were medically unnecessary, lacked a medically accepted indication, or were not issued in the usual course of professional practice.”

Prescriptions were for extremely high doses and excessive quantities, which “fed opioid dependence and addiction,” the DOJ said. Some prescriptions were refilled even before an existing one was due to run out, the complaint alleged.

“By doing so, Rite Aid violated its legal obligations and significantly contributed to this country’s opioid crisis,” the DOJ said.

Rite Aid pharmacists were diligent about tracking suspicious prescribers, but the company ignored the evidence and directed its district managers and pharmacists to delete any internal notes about suspicious prescribers, the DOJ alleged.

Three whistleblowers, all former Rite Aid pharmacy employees, filed their suit in October 2019 under the qui tam provisions of the False Claims Act (FCA). If the federal government’s lawsuit is successful, the whistleblowers would receive a portion of the payment.

The DOJ is alleging hundreds of thousands of violations across five counts, including submission of false claims, using false records or statements, unlawful dispensing of controlled substances, payment by mistake of fact, and unjust enrichment.

“These practices opened the floodgates for millions of opioid pills and other controlled substances to flow illegally out of Rite Aid’s stores,” Associate Attorney General Vanita Gupta said in a press release.

The complaint against Rite Aid, which has more than 2,000 pharmacies nationwide, is the latest in a series of federal, state, and local suits against opioid manufacturers, pharmacies, and others alleged to have fueled the opioid epidemic that has gripped the United States for more than a decade.

In July, Rite Aid reached a $10.5 million settlement with counties in Georgia, North Carolina, and Ohio concerning opioid prescriptions. In August, CVS and Walgreens were ordered to pay $650.6 million to two Ohio counties, the first jury trial to levy damages against retailers.

In November, Walmart agreed to pay $3.1 billion to resolve all potential state lawsuits it faced for its part in the opioid epidemic. CVS and Walgreens that same month agreed to pay approximately $5 billion each to settle their nationwide opioid liabilities.

Rite Aid did not respond to a request for comment.