WASHINGTON — The Justice Department is suing Walmart, alleging the company unlawfully dispensed controlled substances through its pharmacies, helping to fuel the opioid crisis in America.

The civil complaint being filed Tuesday points to the role Walmart’s pharmacies may have played in the crisis by filling opioid prescriptions and by unlawfully distributing controlled substances to the pharmacies during the height of the opioid crisis. Walmart operates more than 5,000 pharmacies in its stores around the country.

The Justice Department alleges Walmart violated federal law by selling thousands of prescriptions for controlled substances that its pharmacists “knew were invalid,” said Jeffrey Clark, the acting assistant attorney general in charge of the Justice Department’s civil division.

Federal law required Walmart to spot suspicious orders for controlled substances and report those to the Drug Enforcement Administration, but prosecutors charge the company didn’t do that. Walmart couldn’t immediately be reached for comment.

“Walmart knew that its distribution centers were using an inadequate system for detecting and reporting suspicious orders,” said Jason Dunn, the U.S. attorney in Colorado. “As a result of this inadequate system, for years Walmart reported virtually no suspicious orders at all. In other words, Walmart’s pharmacies ordered opioids in a way that went essentially unmonitored and unregulated.”

Clark said Walmart “violated important provisions of the Controlled Substances Act that were meant to prevent such controlled substances, including prescription opioids, from being diverted for misuse and abuse.”

AP reported the news of the lawsuit ahead of the Justice Department’s public announcement, citing a person who could not discuss the matter publicly before the announced move. The person spoke to the AP on condition of anonymity.

The Justice Department’s lawsuit comes nearly two months after Walmart filed its own preemptive suit against the Justice Department, Attorney General William Barr and the Drug Enforcement Administration.

In its lawsuit, Walmart said the Justice Department’s investigation — launched in 2016 — had identified hundreds of doctors who wrote problematic prescriptions that Walmart’s pharmacists should not have filled. But the lawsuit charged that nearly 70% of the doctors still have active registrations with the DEA.

Walmart’s lawsuit alleged the government was blaming it for the lack of regulatory and enforcement policies to stem the crisis. The company is asking a federal judge to declare the suit has no basis to seek civil damages; the suit remains ongoing.

The initial investigation was the subject of a ProPublica story published in March. ProPublica reported that Joe Brown, then U.S. attorney for the Eastern District of Texas office, spent years pursuing a criminal case against Walmart for its opioid prescription practices, only to have it stymied after the retail giant’s lawyers appealed to senior officials in the Justice Department.

Two months later, Brown resigned. He didn’t give a reason for his departure except to say he would be “pursuing opportunities in the private and public sectors” and that “some of those will become apparent in the coming days.” Brown went into private practice in the Dallas area.