Samsung Group chief Jay Y. Lee was questioned by South Korea's special prosecutor for more than 15 hours as part of an investigation into a graft scandal that threatens to topple President Park Geun-hye.
The 48-year-old executive, the third-generation leader of the country's top conglomerate, made no comment as he was shown on live television leaving the prosecutor's office in southern Seoul in a black car early on Tuesday.
Lee, who has denied allegations of bribery through Samsung Group spokespeople, had arrived at the office on Monday morning.
South Korea's special prosecutor has focused on Samsung Group's relationship with Park, accusing Lee in his capacity as Samsung chief of pledging 43 billion won to a business and organisations backed by Park's friend, Choi Soon-sil, in exchange for support of a 2015 merger of two Samsung companies.
Proving illicit dealings between Park or those linked to her and Samsung Group is critical for the special prosecutor's case that ultimately targets Park, analysts have said.
The prosecution has also identified four other Samsung executives as suspects and have summoned three of them.