Ask a Korean if the devil wears Prada, and the answer is likely to be yes.

The "devil" in question here is Ms Choi Soon Sil - a cult-linked woman accused of manipulating South Korean President Park Geun Hye and dictating how she runs the country, in the biggest political scandal to rock South Korea in the country's history.

And the shoe? Well, Ms Choi, 60, lost a black Prada loafer while wading through a media mob to get to the prosecutor's office last Monday for investigations. She has been arrested on several charges, including abuse of authority and fraud.

The expensive footwear, which has spawned numerous memes, is seen as evidence of her lavish lifestyle and raised further questions about how she got her money. They included whether it has anything to do with the two non-profit foundations, Mir and K-Sports, she started in the past one year and for which she raised about 80 billion won (S$97 million) within days by arm- twisting conglomerates to donate.

Stories have also emerged in the media of how Ms Choi was arrogant and abused her link to the President, a friend of 40 years. One has it that she arrived at a neighbourhood mini-mart 30 minutes before opening time and yelled: "Open up! Do you know who I am?" The security guard who tried to stop her apparently lost his job the next day.

The snowballing scandal has caused public outrage, with people lashing out at how ridiculous it is for a head of state to be controlled by a "shamanistic adviser" who does not hold any government position but yet is able to enter and leave the presidential Blue House freely, suggest policies and place her cronies in important posts in various government agencies.

People also could not believe how Ms Choi, who has been labelled "empress dowager" and "female Rasputin", managed to pull wool over Ms Park's eyes.

In a national address last Friday, Ms Park, who is estranged from her two siblings, said she had no one else to turn to but Ms Choi.

"I trusted her because she had stayed by my side through the most difficult times of my life. But now, looking back, I realise that my over-reliance on her had blinded my objectivity and allowed my guard to drop," she said.

Ms Choi is the fifth daughter of religious cult figure Choi Tae Min, who mentored both Ms Park and her father, the late President Park Chung Hee. Mr Choi married six times and had nine children. He had Ms Choi with his fifth wife.

Ms Choi was first introduced to Ms Park by her father in 1974. The two women became good friends, and Ms Choi often played the role of companion and personal aide to Ms Park.

Observers said they were as close as sisters, but there were many differences between them too.

While Ms Park was living in isolation after her father's death in 1979, Ms Choi reportedly studied early childhood education at Pacific State University in the US.

Back in South Korea, she worked with young children, first as the vice-principal of a kindergarten in south-eastern city Daegu from 1988 for five years, and then running another kindergarten in Seoul's upscale Gangnam district.

But she is now suspected of forging her academic background after local radio station CBS found out that the university did not offer any early childhood education course at the time she claimed she was there.

Unlike Ms Park, who never married, Ms Choi is twice divorced. Her first marriage to a Daegu man ended after four years in 1986. Ten years on, she married her father's assistant and gave birth to a daughter. They split up in 2014.

Now single, Ms Choi is rumoured to be dating a man 20 years younger than her, former fencer Ko Young Tae, 40. He is said to be part of a team of advisers called "Eight Fairies", created by Ms Choi to unofficially help Ms Park with state policies.

The term, which has its origins in folklore, can refer to a dance performed during the Joseon Dynasty (1392-1910) or, in modern times, a shamanistic ritual or a gathering of rich men's wives.

Another "fairy" is Ms Choi's confidante, film director Cha Eun Taek who shot the music video for K-pop star Psy's 2014 single Hangover and is involved in numerous big projects supported by the Ministry of Culture.

To Ms Park, Ms Choi was a loyal friend who gave her strength in her darkest periods. Their unusual friendship has fuelled at least two scandals in the past, including a 2014 episode in which Ms Choi and her ex-husband, Mr Chung Yoon Hoi, who had served as Ms Park's aide, were accused of influence peddling.

When news of this latest scandal broke in September, Ms Choi fled to Germany, where her daughter, now 20, is training in horseriding.

Ms Choi returned to South Korea last Monday to submit herself to investigations.

Observers said she had to save her old friend from being toppled, which would have destroyed her own web of influence.

The saga is ongoing, but their friendship may be over.

Ms Park, in her Friday speech, said: "I will sever all ties and live in solitude from now on."

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