Jailed former first lady Kim Keon-hee will return to the special counsel’s office on Thursday for a third round of questioning since her detention.
The special team said in a notice to the press on Tuesday that the inquiry, originally set for Wednesday, has been postponed.
Earlier in the day, Kim submitted a handwritten letter citing poor health.
Investigators plan to grill her over allegations that she accepted luxury gifts from the Unification Church through Jeon Sung-bae, a shaman.
Earlier sessions last Thursday and Monday focused on charges that she colluded with political broker Myung Tae-kyun in election meddling and participated as a financier in the 2009–2012 Deutsch Motors stock manipulation scheme.
Kim faces multiple indictments including violations of the Capital Markets Act, Political Funds Act and aggravated bribery statutes.
Separately, Jeon is set to appear before court the same morning for a warrant hearing on accusations he relayed expensive jewelry and influence requests from Unification Church officials to Kim.