South Korea's President Park Geun-hye has become the country's first democratically elected leader to be forced from office.
In 2016, South Korea saw the start of a massive corruption scandal involving its political and business elite that brought down its first female president Park Geun-hye.
That dubious honour was imposed on her when, on 10 March, judges unanimously upheld parliament's decision in December to impeach her over a corruption scandal.
The scandal, which continues to ripple through South Korean society, has generated huge protests.
That scandal, which has generated huge protests, centres on her relationship with an old friend, and has brought allegations of cult activities, influence-peddling and leaks of classified information.
It has centred on Ms Park's relationship with an old friend, Choi Soon-sil, and has brought to the surface allegations of cult activities, influence-peddling and leaks of classified information.
What is the relationship at the heart of the scandal?
What is the relationship at the heart of the scandal?
In 1974, Park Geun-hye's mother was killed by a North Korean spy who had intended to kill Ms Park's father, then-military leader Park Chung-hee. Ms Park, then aged 22, became a stand-in first lady for her widowed father.
In 1974, Park Geun-hye's mother was killed by a North Korean assassin.
It was then she got to know Choi Tae-min, a pseudo-Christian leader who set up a cult called The Church of Eternal Life. He said he had been visited by the soul of Ms Park's late mother who asked him to guide her.
Ms Park, then aged 22, became a stand-in first lady for her widowed father, then-military leader Park Chung-hee.
He became Ms Park's mentor, while also amassing considerable wealth and power.
She got to know Choi Tae-min, a pseudo-Christian cult leader dubbed "the Korean Rasputin".
When President Park senior was assassinated by his head of intelligence in 1979, there was speculation it was because the spy chief was worried the president was being manipulated by the man dubbed "the Korean Rasputin".
He became a close family friend and Ms Park's mentor, while also amassing considerable wealth and power.
By this point Ms Park was firm friends with Mr Choi's daughter, Choi Soon-sil. Their critics believe Ms Choi perpetuated her father's habits.
Ms Park's father was assassinated in 1979. By this point she was firm friends with Mr Choi's daughter, Choi Soon-sil, who later became her adviser when Ms Park became president.
Their critics believe Choi perpetuated her father's habits, and some media reports suggested that Ms Park held shamanist rituals at the presidential compound under Choi's influence, which Ms Park denied.
Why has the friendship become problematic?
Why has the friendship become problematic?
On 20 November, Ms Choi was charged with various offences, including abuse of authority, coercion, attempted coercion and attempted fraud. She is now on trial.
In June 2017, Choi was jailed for three years for corruption, after she was found guilty of using her position to solicit favours for her daughter.
Few claims have been off-limits in the media coverage, with some reports going as far as suggesting the president is a puppet who hosted shamanist rituals at the presidential compound. But many of the lurid claims are unsubstantiated.
She still faces trial for various offences, including abuse of authority, coercion, attempted coercion and attempted fraud.
Ms Choi is accused of using her presidential connections to pressure companies for millions of dollars in donations to two non-profit foundations she controlled.
One of the main accusations levelled against Choi was that she used her presidential connections to pressure conglomerates - including electronics giant Samsung - for millions of dollars in donations to two non-profit foundations she controlled.
The claims have even swept up Samsung in the investigation - the firm is one of eight that has admitted making payments to the foundation, but denies it did so in return for any favours.
Ms Park meanwhile has been accused of colluding with Choi.
President Park is alleged to have been personally involved, instructing Ms Choi and two presidential aides to collect money for the launch of Ms Choi's foundations, according to prosecution documents submitted to the court.
Ms Park was officially ousted in March 2017, following parliament's decision to impeach her in December. She was the country's first democratically-elected president to be forced from office.
Ms Choi is also accused of having received large numbers of confidential government documents from Ms Park, via an aide. These allegedly included information about ministerial candidates and North Korea.
After losing her presidential immunity, she was charged with bribery, abusing state power and leaking state secrets, and her trial began in May.
There are even claims Ms Choi took advantage of the president's wardrobe budget - buying cheap outfits and keeping the change.
Choi is also accused of having received large numbers of confidential government documents from Ms Park, via an aide.
What do the two women say?
Both women have since denied wrongdoing. They had earlier apologised, but it was unclear exactly what they were apologising for.
They have both apologised, but it remains unclear exactly what for.
Choi said she had committed an "unpardonable crime", though her lawyer said this was not a legal admission of guilt.
When she was first questioned in October, Ms Choi said she had committed an "unpardonable crime", though her lawyer said this was not a legal admission of guilt.
Ms Park admitted she had committed lapses, and apologised to the public for causing "national concern".
President Park has herself admitted some lapses. She says she did consult Ms Choi for advice, and that she helped her edit her speeches, but that this stopped once she had a team of advisers in place.
Witnesses have claimed that Ms Choi received briefings and official papers long after that occurred. Documents were also discovered on an unsecured tablet computer found in an old office of Ms Choi's.
The tone of the president's pronouncements has changed over time. She began with opaque apologies: "Regardless of what the reason may be, I am sorry that the scandal has caused national concern and I humbly apologise to the people."
But she has moved on to "heartbroken" public confessions of naivety: "Sad thoughts trouble my sleep at night. I realise that whatever I do, it will be difficult to mend the hearts of the people, and then I feel a sense of shame."
She had said she was willing to be questioned by investigators, but has so far resisted their attempts to speak to her.
Her spokesman said the prosecutors' allegation that she colluded with Ms Choi was "deeply regrettable" and "but a house of cards built on repeated imagination".
So how is Samsung involved?
So how is Samsung involved?
Samsung's de facto head, Lee Jae-Yong, is now on trial on a string of corruption charges, including bribery and embezzlement.
The firm is one of eight that has admitted making payments to the foundation, but denies it did so in return for any favours.
Prosecutors allege Mr Lee, heir to South Korea's largest conglomerate, approved payments of 41bn won ($36m, £29m) to Ms Choi's foundations, to win government support for a big restructuring of Samsung.
In August 2017, Samsung's de facto head, Lee Jae-yong, was jailed for five years for bribery and embezzlement.
He denies the allegations, as do four other Samsung executives facing trial.
Lee was convicted over payments of 43bn won ($36.4m; £30.3m) made to Choi's foundations, as well as for giving a horse and several million dollars to assist the equestrian career of Choi's daughter.
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 had accused Lee of approving these payments and gifts in order to win government support for a major restructuring of Samsung.
In a December parliamentary hearing, Samsung admitted giving a total of 20.4bn won to two foundations, but denied seeking favours.
The 2015 merger of two Samsung units, which paved the way for Lee to become the eventual head of South Korea's largest conglomerate, sparked controversy at that time.
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 regretted.
While Lee did not dispute that the payments were made, he maintained during his trial that he was not involved in the decisions and denied that he sought government favours.
Investigators are assessing whether the payments bought support for a controversial merger of two Samsung affiliates.
Lee was also found guilty of hiding assets overseas, concealing criminal proceeds, and perjury. He is appealing against his conviction.
Some investors opposed the deal, saying one of the affiliates's shares were undervalued, but support from a major shareholder, the state-run National Pension Service (NPS), helped the deal go through.
Who is Samsung's Lee Jae-yong?
The official who oversaw the NPS has since been charged with putting pressure on managers to approve the merger, which strengthened Mr Lee's control over a key part of the conglomerate.
Is anyone else involved?
Is anyone else involved?
Several former presidential aides have been investigated.
A host of other players have either been implicated, investigated or jailed in connection with the wide-reaching scandal.
An Chong-bum, Ms Park's former senior secretary for policy co-ordination, has been charged with abuse of authority, coercion and attempted coercion, and Jung Ho-sung is accused of passing classified presidential documents to Ms Choi.
These include Samsung executives, various figures in the entertainment world, a former minister, presidential aides, university officials and former associates.
Local media have also been busy finding colourful associates of Ms Choi who were close to the president, including various celebrities and her personal trainer, who was appointed as a presidential aide.
One of them is Choi's daughter, Chung Yoo-ra, a former national equestrian and recipient of Samsung's gift horse.
What now?
Choi was convicted for influencing officials at Ms Chung's university to admit her daughter and give her grades for papers or exams she never took.
The impeachment verdict against Ms Park stripped her of presidential immunity.
Prosecutors say Ms Chung was involved in or had knowledge of several of her mother's crimes, but she has denied it.
Prosecutors then charged her with bribery, coercion, abuse of power and leaking state secrets in April 2017. Preliminary hearings in her trial began in early May.
She was extradited to South Korea from Denmark in early 2017, but has not been detained.
How has the scandal affected South Korean society?
Since it began the whole affair has prompted numerous mass protests in South Korea, many of which called for Ms Park to step down.
It has fuelled discontent against the government, the political elite and family-run conglomerates which dominate South Korea's economy.
Though Choi and Lee have been convicted, many are still waiting to see what happens in Ms Park's court case which is due to be wrapped up in the coming months.
For many South Koreans, the former president who has been at the centre of one of the country's biggest scandals still has a lot to answer for.
