Samsung's de facto head Lee Jae-Yong has gone on trial in South Korea on charges of bribery.
The case is linked to a massive scandal that led to the impeachment of President Park Geun-hye.
Mr Lee is accused of giving donations to non-profit foundations operated by Choi Soon-sil, a friend of Ms Park, in exchange for government favours.
Mr Lee, the Samsung group and four other Samsung executives who are also on trial all deny wrongdoing.
Mr Lee did not appear in person on the opening day of the trial in the capital, Seoul,
The trial is expected to go on for several months.
The case against Lee
Mr Lee, also known as Jay Y Lee, is currently vice-chairman 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.
Prosecutors have accused Mr Lee of giving donations worth 41bn won ($36m;£29m) to organisations linked to Ms Park's close friend Ms Choi. They alleged this was done to win government support for a big restructuring of Samsung that would help a smooth leadership transition in favour of Mr Lee, who is standing in as chairman for his ill father.
The controversial merger required support from the national pension fund - the allegation is that this support was granted in return for the donations.
In a December parliamentary hearing, Samsung admitted giving a total of 20.4bn won to two foundations, but denied seeking favours in return.
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 regrets.
Grandson of Samsung founder Lee Byung-chul, son of current chairman Lee Kun-hee.
- Also known as Jay Y Lee, the 48-year-old has spent his entire career in the company.
- Is vice chairman of Samsung Electronics and was nominated to join the firm's board in October 2016.
- Despite his arrest, still widely expected to take overall control of Samsung.
- Critics say his rise through Samsung has been due to his birth, not his business experience.
Ms Park's position began to unravel in October last year when details of her friendship with Ms Choi emerged.
They included revelations that the president had allowed her old friend - who holds no government role - to edit political speeches.
Politicians voted in December last year to impeach her over the scandal. South Korea's constitutional court is expected to rule shortly on whether that decision will be upheld.
Until then, Ms Park remains formally president but stripped of her powers.
Ms Choi is on trial for charges including corruption and coercion.
Ms Park denies wrongdoing but has apologised for the way she managed her relationship with Ms Choi, who also denies committing criminal offences.