— South Korean prosecutors on Sunday said they believe President Park Geun-hye conspired in the criminal activities of a confidante who allegedly manipulated government affairs and exploited her presidential ties to amass an illicit fortune — a damning revelation that may convince opposition parties to push for Park’s impeachment.

Prosecutors are planning to question Park, who has immunity but can be investigated, said Lee Young-ryeol, chief of the Seoul Central Prosecutors’ Office.

Prosecutors on Sunday formally charged Park’s longtime friend Choi Soon-sil on suspicion of interfering with state affairs and bullying companies into giving tens of millions of dollars to foundations she controlled.

Lee said at a news conference that evidence showed “the president was involved as a conspirator in a considerable part of the criminal activities by suspects Choi Soon-sil, Ahn Jong-beom and Jung Ho-sung,” referring to two presidential aides charged Sunday with helping Choi.