The firm is accused of giving large donations to non-profit foundations operated by Choi Soon-sil, a close confidante of Ms Park.
The donations were allegedly given in exchange for political support of a controversial merger.
Ms Choi has been charged with coercion and attempted fraud.
According to South Korea's Yonhap news agency, Choi Gee-sung, a Samsung vice chairman, and Chang Choong-ki, a president at the group, were being interviewed on Monday by special prosecutors about the corruption allegations.