The Connecticut-based maker of the powerful painkiller OxyContin and three of its current and former executives pleaded guilty Thursday to misleading the public about the drug's risk of addiction, a federal prosecutor and the company said.

Purdue Pharma L.P. and the executives will pay $634.5 million in fines, U.S. Attorney John Brownlee said in the news release.

The plea comes two days after the Stamford, Conn.-based company agreed to pay $19.5 million to 26 states and the District of Columbia to settle complaints that it encouraged physicians to overprescribe OxyContin.

"With its OxyContin, Purdue unleashed a highly abusable, addictive, and potentially dangerous drug on an unsuspecting and unkowing public," Brownlee said. "For these misrepresentations and crimes, Purdue and its executives have been brought to justice."