Lee Jae-yong has already been quizzed by politicians over the scandal at a parliamentary hearing.
Samsung heir-apparent Lee Jae-yong is to be interviewed as a suspect in a corruption scandal surrounding the impeached South Korean president. The firm is accused of giving donations to non-profit foundations operated by Choi Soon-sil, a confidante of President Park Geun-hye. The donations were allegedly made in exchange for political support of a controversial merger. Mr Lee will face special prosecutors on Thursday, officials said. Samsung declined to comment. Mr Lee is currently vice-president of Samsung Electronics. But since his father, Lee Kun-hee, suffered a heart attack in 2014, he is considered de facto boss of the entire Samsung Group conglomerate.
Politicians voted on 9 December to impeach President Park over the scandal - a decision South Korea's constitutional court has six months to uphold or overturn. Until then she remains formally president but stripped of her powers, which are handed to the prime minister, a presidential appointee. The claims circle around a merger between the electronics giant's construction arm, Samsung C&T, and an affiliate firm, Cheil Industries.
Prosecutors allege that Samsung gave €2.8m euros ($3.1m; £2.5m) to a company co-owned by Ms Choi and her daughter, in return for Ms Park's support for the deal. Lee Jae-yong has already given evidence to politicians over the scandal, but this is the first time he will be quizzed as a suspect by investigators. At the parliamentary hearing in December Samsung admitted giving a total of 20.4bn won (£16m; $17.46m) to the two foundations, but denied seeking favours.
And Mr Lee also confirmed the firm gave a horse and money to help the equestrian career of Ms Choi's daughter, Chung Yoo-ra, something he said he now regretted. Earlier this week two other Samsung executives were interviewed by the special prosecutors, but were treated as witnesses rather than suspects.