president Park Geun-Hye

South Korean prosecutors on Thursday demanded a 25-year prison sentence for the powerful secret confidante of ousted president Park Geun-Hye, who was at the centre of the sprawling corruption scandal that brought down the head of state.

Choi Soon-Sil was "the alpha and omega of the scandal", a prosecutor told the Seoul Central District Court, adding the prosecution "demands 25 years in prison for the accused Choi