NORMAN, Okla. — A key witness in the ongoing trial against the nation’s largest drugmaker described the company as the “kingpin” in the state’s opioid crisis.

Dr. Andrew Kolodny, co-director of opioid policy research at Brandeis University, testified Thursday he believed Johnson & Johnson was a “major cause” of the epidemic. The company is being sued by the state of Oklahoma, accused of fueling the opioid epidemic through deceptive marketing and downplaying the risks of addiction.

“In 2007, when Purdue Pharma was convicted criminally of claiming that OxyContin was less addictive because of its extended release formulation, Johnson & Johnson continued to sell opium and oxycodone to Purdue Pharma and continued to do exactly what Purdue Pharma was convicted criminally of doing,” Kolodny said. “It was Johnson & Johnson’s opium that flooded into the United States.”

He added the company then continued to promote their own products as having “lower abuse potential.”

Kolodny first took the stand on Tuesday after the state presented him as an expert witness, but defense attorneys objected to him being considered an expert on the subject. They argued Kolodny was not qualified to testify on the cause of the epidemic because his research primarily relies on correlation, not causation.

“Those are different things,” attorney Michael Yoder stated.

On Thursday, the defense continued to build their argument that Kolodny has not provided any evidence showing addiction or deaths in Oklahoma were actually caused by a doctor misled into prescribing their drugs.

Yoder: “You have some strongly held personal opinions. I’m not asking what they are right now. I’m just asking you if you agree that there are strongly held opinions.”

Dr. Kolodny: “Yes, I would imagine I would have some strongly held opinions.”

The trial continues on Friday.