South Korean police on Monday summoned the wife of Korean Air Chairman Cho Yang-ho to question her about allegations she abused and assaulted employees.
Lee Myung-hee has been accused of physically or verbally abusing more than 10 former and current employees of Cho's Hanjin conglomerate, the parent of Korean Air.
Lee told reporters she felt "sorry for causing troubles" after arriving at a Seoul police agency for questioning Monday.
The Cho family has been under mounting public criticism after company employees alleged they were subjected to mistreatment and tantrums.
Lee's eldest daughter, Cho Hyun-ah, who was formerly the head of the airline's cabin service, received worldwide notoriety in 2014 after her onboard "nut rage" tantrum delayed a flight. She was sentenced to one year in prison for violating aviation law but was released early when a higher-level court suspended the sentence.
Last week, Cho Hyun-ah was investigated by South Korean immigration officials over allegations that she unlawfully hired housekeepers from the Philippines.
Cho Hyun-ah's younger sister, Cho Hyun-min, is under investigation for allegedly hurling a cup of water during a business meeting.
South Korean authorities are also looking into suspicions that the Cho family, including Cho Yang-ho, evaded taxes and used airline services to smuggle luxury goods.