Story highlights President Park will be the first sitting South Korean leader to be investigated

A confidante and two former aides of Park's face corruption charges

(CNN) South Korean President Park Geun-hye will be investigated "as a suspect" in a growing political corruption scandal, prosecutors said on Sunday, as three people with ties to Park were officially indicted.

But whatever their findings, Park will not be charged due to a law that makes the president immune from prosecution.

South Korean prosecutors announced Sunday there was enough evidence charge Choi Soon-sil, a friend of the president, and former aides An Chong-bum and Chung Ho-sung.

Lee Young-ryol, the prosecutor who led the corruption probe, said Choi and An are being charged with abuse of power, fraud and coercion. Chung faces charges related to leaking classified documents to Choi through email, phone and fax.

"Park cannot be charged with any 'crime' as a sitting president in accordance with Korean constitution but prosecutors will continue to investigate Park Geun-hye," Lee said.

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