Jim Geldhof, shown this month in Lake Orion, Mich., is a retired DEA diversion supervisor. He grew increasingly frustrated by his inability to persuade the agency’s headquarters to approve cases at a time when opioid deaths were soaring. (Nick Hagen/For The Washington Post)

Two senators asked Attorney General Loretta E. Lynch Wednesday to explain a sharp drop in the number of enforcement actions against large pharmaceutical distributors and others by the Drug Enforcement Administration.

Sen. Patrick J. Leahy (D-Vt.) and Sen. Ron Wyden (D-Ore.) requested a wide variety of information about cases brought by DEA’s Diversion Control Division in the wake of a Washington Post investigation published over the weekend.

The DEA division enforces laws written to prevent the diversion of opioid painkillers to the black market, where they can fall into the hands of substance abusers and drug dealers.

The senators’ four-page letter asks Lynch to explain why the office has filed few administrative charges in recent years, whether a law approved by Congress earlier this year has hamstrung the diversion division and what standard the DEA uses before deciding to take an enforcement action.

As the worst of a nationwide opioid epidemic raged in Appalachia, DEA investigators went after companies distributing millions of highly addictive pills. Then, their cases ground to a halt. (Lee Powell/The Washington Post)

The senators also asked for more information about a 2015 settlement with pharmaceutical giant McKesson that has remained largely confidential aside from the company’s disclosure in federal filings that it would pay a $150 million fine for its actions. And the lawmakers asked why no fine has been levied against Cardinal Health, another major distributor, despite a settlement in a diversion case against the company in 2012.

The senators singled out a drop in cases from 131 in 2011 to 40 in 2014.

“This startling decrease in enforcement activity occurred just as our nation began to confront the scope of the opioid epidemic — and just as the over-prescription of powerful opioid painkillers was recognized as a major driver of the crisis,” Leahy and Wyden wrote.

About 165,000 people have died of painkiller overdoses between 2000 and 2014.

Leahy is the ranking Democrat of the Senate Judiciary Committee, which oversees criminal justice and drug enforcement policy. Wyden is the ranking Democrat of the Senate Finance Committee, which oversees the Medicare and Medicaid programs.

By 2020, Leahy and Wyden wrote, public and private spending on substance abuse treatment is expected to reach $42.1 billion, and Medicare and Medicaid will account for a third of that spending.

Justice Department spokesman Peter Carr said, “We will review the letter.”

The Post reported Sunday that, beginning in 2013, DEA lawyers started to delay and block enforcement efforts against large opioid distributors and others, requiring investigators in the field to meet a much higher burden of proof before they could take action. The slowdown came despite the continued high death toll from overdoses of prescription narcotics that has plagued the country for years.

Five former DEA supervisors told The Post that they were alarmed and frustrated by the sharp drop in enforcement actions. The supervisors’ concerns were echoed in reports filed by the DEA’s chief administrative law judge that were obtained by The Post under the Freedom of Information Act.

Investigators said they unsuccessfully confronted Clifford Lee Reeves II, the attorney in charge of the DEA unit that approves administrative cases against people and companies suspected of diverting painkillers to the black market.

“It was like he was on their side, not ours,” said Jim Geldhof, the diversion program manager in the Detroit field office when Reeves took over in late 2012. “I don’t know what his motive was, but we had people dying. You’d think he’d be more aggressive. We were in the throes of a major pill epidemic.”

The former head of the diversion office, Joseph T. Rannazzisi, said he was summoned to an unusual meeting in 2012 with then-Deputy Attorney General James M. Cole. Rannazzisi said the meeting came during an investigation of Cardinal Health and CVS Health, and he said he was and chastised “for going after industry.” Cole told The Post he was trying to ensure that Rannazzisi was getting all of the facts from the companies. Rannazzisi was replaced in 2015 and retired from DEA later that year.

After stories appeared in The Post, acting DEA Administrator Chuck Rosenberg sent an agency-wide message.

“Recent articles in The Washington Post criticized our historical management of administrative diversion cases,” the message read. “Are there things we need to fix? You bet. We can — and should — learn from fair and thoughtful criticism. Such criticism can be painful, but we ignore it at our peril. . . .

“What we simply cannot do is impugn the integrity and motives of those people with whom we argue or disagree. The personalization of professional disagreements is unfair and corrosive. I was appalled that some people thought it ok to attack the integrity and motives of their former colleagues.”