South Korean investigators raided the office of the National Pension Service, the world's third-largest pension fund, on Wednesday in their probe over a corruption scandal that led to parliament's recent vote to impeach the president.
A special prosecutor investigating the scandal is looking into the NPS decision last year to approve the $8 billion merger of two Samsung Group affiliates, an official from the special prosecutor's office said.
The NPS was a major shareholder of both affiliates.
The merger was criticized for strengthening the founder family's control of the group at the expense of other shareholders.
Investigators are examining whether Samsung's support of a business and foundations backed by President Park Geun-hye's longtime friend Choi Soon-sil may have been connected to the service's support of the deal, the prosecution official said on Wednesday.
Choi is in custody and on trial for fraud and abuse of power in the influence-peddling scandal.
On Wednesday, prosecutors also raided an office at the Ministry of Health and Welfare, which administers the NPS.
A Ministry of Health and Welfare spokeswoman confirmed that special prosecution officials were at the ministry's pension department and "looking at a broad range of material."
The pension service's backing of last year's merger of Samsung C&T Corp. and Cheil Industries was seen as crucial to the deal winning shareholder approval.
Parliament voted on Dec. 9 to impeach Park, a decision that must be confirmed or overturned by the Constitutional Court.
Last month, a different team of prosecutors raided offices of Samsung and the NPS.