South Korean investigators Wednesday raided the state-run National Pension Service in a widening probe into a corruption scandal that has engulfed President Park Geun-Hye and large companies including Samsung.
A special prosecutor has been investigating whether Samsung bribed Park's confidant Choi Soon-Sil to win state approval for a controversial merger of two of its units.
Investigators also said they had sought an arrest warrant for Choi's daughter Jeong Yu-Ra, who is now at large in Europe. Jeong is accused of bribing her way into a college in Seoul.
The merger of Samsung units Cheil Industries and Samsung C&T last year was seen as a crucial step to ensure a smooth father-to-son power transfer to Lee Jae-Yong, scion of Samsung's founding family.
It was criticised by many who said it wilfully undervalued Samsung C&T stock, but the National Pension Service (NPS) - a major Samsung shareholder - voted in favour of the deal, which eventually went through.
Investigators searched some 10 places including offices of the NPS and the health ministry that oversees the fund, Yonhap news agency said.
The NPS oversees 543 trillion won (S$666 billion) in funds, making it the world's third largest public pension fund.
NPS offices were raided last month by different prosecutors, who also searched Samsung Group offices.
The special prosecutor has taken the case over from state prosecutors.
Choi has been formally indicted on charges of abuse of power and coercion.
She is accused of leveraging her personal relationship with Park to coerce donations from big firms like Samsung to two non-profit foundations which was then used for Choi's personal gain.
Prosecutors say Park colluded with Choi to extract money from the firms and will question the president as a subject in a criminal investigation.