Massachusetts sued a unit of French advertising company Publicis Groupe SA on May 6, accusing it of fueling the U.S. opioid crisis by using unfair and deceptive marketing to help drugmaker Purdue Pharma sell more OxyContin.

Purdue Pharma LP filed a bankruptcy plan on March 15 that would resolve thousands of opioid lawsuits by restructuring the OxyContin maker into an entity that would steer profits to plaintiffs and require the company’s Sackler family owners to contribute nearly $4.3 billion to the settlement.

Purdue Pharma LP pleaded guilty to criminal charges over the handling of the company’s addictive prescription painkiller OxyContin, capping a deal with federal prosecutors to resolve an investigation into the drugmaker’s role in the U.S. opioid crisis.