McKinsey & Co. has agreed to pay $650 million to resolve a U.S. Department of Justice investigation into the consulting firm's work advising opioid manufacturer OxyContin maker Purdue Pharma on how to boost sales.

McKinsey has entered into a deferred prosecution agreement filed in federal court in Abingdon, Virginia, to resolve criminal charges brought as part of a rare corporate prosecution concerning the marketing of addictive painkillers that helped fuel the deadly U.S. opioid epidemic.

A former senior partner at McKinsey, Martin Elling, has also agreed to plead guilty to obstruction of justice, according to court papers.