Visiting NFL teams were met Sunday by federal Drug Enforcement Administration agents Sunday as part of an ongoing investigation into the handling and distribution of prescription painkillers, ESPN reported.

While no arrests were expected and search warrants not issued, per the report, a federal law enforcement official told “Outside the Lines” the inspections were motivated by allegations raised in a May 2014 federal lawsuit, filed on behalf of several prominent NFL players, who allege team physicians and trainers routinely gave them painkillers in an illegal manner to mask injuries and keep them on the field.

A 2011 study funded partially by the U.S. Department of Health and Human Services found retired NFL players misuse opioid pain medications at a rate more than four times that of the general population. The same study revealed that 71 percent said they misused the drugs while playing in the league and 15 percent said the abuse continued in 2011.

“DEA agents are currently interviewing NFL team doctors in several locations as part of an ongoing investigation into potential violations of the Controlled Substances Act,” DEA spokesperson Rusty Payne told ESPN on Sunday. “The Drug Enforcement Administration has a responsibility under the Controlled Substances Act to ensure that registrants who possess, prescribe and dispense controlled substances are following the law.”

ESPN, citing sources, said officials were focusing on the Tampa Bay Buccaneers and the San Francisco 49ers. The Buccaneers played at Washington; the 49ers played the Giants in East Rutherford, N.J.

A federal lawsuit filed in California that includes 10 named plaintiffs, including Jim McMahon, Richard Dent and Keith Van Horne of the 1985 Chicago Bears, could be expanded to well over 1,200 plaintiffs if distinguised as a class-action case.

DEA agents told ESPN on Sunday that some of their intelligence on current teams suggest specific pills and medication is not logged to specific players, which is illegal. McMahon, who played quarterback for the Bears and also suffers from memory loss, said players in 1985 were essentially given unlimited access to painkillers. He said he became addicted to the extent that he was taking 100 Percocet pain-killing pills per month, even in the offseason.

“I think it’s great that the DEA is taking this seriously. We alleged back on May 20 that the NFL was issuing these controlled substances and prescription medicines in an illegal manner and nobody has really disputed the factual basis of that claim,” Phil Closius, an attorney representing the former NFL players involved in the ongoing federal lawsuit, told ESPN.

Van Horne and McMahon are part of the NFL’s concussion settlement.

McMahon said when the case was filed in San Francisco that he suffered a broken neck and ankle but never told of the seriousness of the injuries. Instead, he received medications and allowed to play with the painful injuries.