Choi Gee-sung, head of Samsung Group's future strategy office, and his deputy Chang Choong-ki appeared in the office of the independent counsel team.
They lead the group's future strategy planning division believed to be the de facto control tower that makes key decisions for Samsung and is closely linked to the ongoing scandal, Yonhap news agency reported.
Samsung is suspected of giving financial support to foundations and a company controlled by Geun-hye' friend Choi Soon-sil, who is at the centre of the scandal, in return for a state-run pension fund's backing of a major merger deal between Samsung subsidiaries in 2015.
The probe team is investigating whether the presidential office Cheong Wa Dae pressured the state fund to support the merger in return for favours Samsung had given to Park's friend, who is standing trial over a string of corruption charges.
"The two were called in to bear witness to the case, but their statuses could change to that of suspect in the course of the interrogation," an official on the investigation team said.
The probe team also summoned Choi Soon-sil but she declined to appear, saying she needs to prepare for her own trial slated for Wednesday and President Park's impeachment hearing Tuesday.