Attorneys, forensic analysts and other financial experts working for Purdue Pharma spent nearly two years looking for evidence of wrongdoing by the Sacklers. Critics want the findings made public.

Under a bankruptcy plan filed late Monday, the OxyContin maker would pay $500 million up front, promising billions in future payments. Twenty-four states rejected the proposal.

Thursday's hearing was the first time members of the Sackler family faced a public accounting for their alleged role in the nation's deadly opioid epidemic.

The corporate consulting giant issued a rare apology for its behind-the-scenes work with Purdue Pharma, maker of OxyContin. One senator called McKinsey's behavior "abhorrent."

A new plea deal with the Justice Department is the second time the family-owned company admitted criminal schemes to boost Oxycontin sales. Despite their hands-on role, the Sacklers face no charges.

The controversial deal hashed out between the Department of Justice and the maker of Oxycontin provides hundreds of millions of dollars of relief for communities hit hard by the opioid epidemic.

Critics say the settlement doesn't hold company executives or members of the Sackler family accountable for their aggressive marketing of OxyContin, which helped fuel the nation's opioid epidemic.