South Korean lawmakers have agreed to the appointment of an independent prosecutor to investigate the scandal involving President Park Geun-hye.

Parliament has signed off on the bill that will have the opposition Minjoo and People’s parties propose candidates for the job of investigating the allegations against the president. The ruling Saenuri Party will be excluded from the process.

The appointed prosecutor will have 120 days to investigate. Former members of Park’s staff are accused of leaking confidential documents to Choi Soon-sil, the president’s confidant. The establishment of foundations presumably controlled by Choi will also be under investigation.