Thirteen drug distribution companies knew or should have known that hundreds of millions of prescription narcotic pills were ending up on the black market, according to an investigation by The Washington Post. These distribution companies ship drugs from manufacturers to consumers.

The findings come from court records, Drug Enforcement Administration (DEA) documents and legal settlements. Some distributors saw signs of illegal activity and continued to send drugs to suspicious pain clinics or pharmacies anyway, the article notes.

“Through the whole supply chain, I would venture to say no one was doing their job,” said Joseph T. Rannazzisi, former head of the DEA’s Office of Diversion Control, who headed the effort against drug distributors from 2005 until shortly before he retired in 2015. “And because no one was doing their job, it just perpetuated the problem. Corporate America let their profits get in the way of public health.”