The woman at the centre of a political row in South Korea has said she “deserves death”, before a meeting with prosecutors examining whether she used her close ties to the president, Park Geun-hye, to pull government strings and amass an illicit fortune.

“Please, forgive me,” Choi Soon-sil, a cult leader’s daughter with a decades-long connection to Park, said through tears inside the Seoul prosecutor’s building, according to Yonhap news agency. Using a common expression of deep repentance, she added: “I committed a sin that deserves death.”

'Rasputin-like' friend of South Korean president returns amid protests Read more

Yonhap and other South Korean media later reported that Choi had been detained, and that prosecutors planned to seek an arrest warrant for her. Telephone calls to the prosecutor’s office were not immediately answered.

Earlier in the day Choi was several times nearly knocked off her feet as she tried to walk through a crowd of journalists, protesters and security surrounding the building’s entrance.

YTN TV said Choi, 60, lost a shoe as the throng converged on her, and a protester reportedly tried to enter the building with a bucket full of animal faeces. Other protesters screamed: “Arrest Choi Soon-sil,” and “Park Geun-hye should resign.”

The scandal exploded last week when, after weeks of speculation, Park acknowledged that Choi had edited some of her speeches and provided public relations help. Widespread media reports say Choi, who has no official ties to the administration, may have had a major role in government affairs.

Choi has previously said she helped Park but did not know whether she had seen confidential information.

Investigators are trying to determine the degree of access Choi had and whether she was given sensitive presidential documents. They have raided the homes of some officials in the presidential Blue House as part of the investigation.

Park has fired some of her closest aides to try to contain the fallout. Some politicians have called for Park’s resignation or impeachment, and thousands of people have protested in the streets.

Facebook Twitter Pinterest People holding placards reading ‘Park Geun-Hye out’ march in Seoul on Saturday. Photograph: Jung Ui-chel/EPA

It is not clear how much influence Choi had. But many South Koreans believe there is much more to the story than Park has acknowledged, and the frenzy surrounding the scandal threatens her presidency.

On Sunday Choi returned home from seclusion in Germany. It was unclear whether any details of her questioning on Monday would be revealed, or how long she would be in the prosecutor’s office. The questioning of Choi’s former associates, including a purported former employee of a host bar, lasted two days.

Choi has been close to Park since Choi’s father, the leader of a religious cult, gained Park’s trust by reportedly convincing her that he could communicate with her assassinated mother. Choi’s father denied this in a media interview in 1990.

The senior government official who later shot and killed Park’s father, the dictator Park Chung-hee, is said to have claimed he staged his attack in part because Park Chung-hee would not keep Choi’s father away from the young Park Geun-hye.

Elected in 2012, Park has long been criticised for an aloof manner and for relying on only a few longtime confidantes. Most South Koreans, however, assumed those confidantes were in the government. That she may have been outsourcing decisions to someone outside of government, and someone connected with a murky, lurid backstory, has incensed many.

Media reports said Choi used her connections to Park to press businesses to give money to two nonprofit organisations that Choi controlled. Choi then allegedly used some of the organisations’ official funds for personal purposes.

South Korean media speculated that the two foundations collected about 80bn won(£57m) in donations from business groups in just a few months.

The president of Ewha Womans University has resigned after allegations that Choi used her connections to Park to get her daughter into the elite school and secure special academic treatment.

Political and business corruption remains widespread in South Korea, which has had full democracy only since the late 1980s, when it shook off decades of military dictatorship. But the current scandal has struck a chord in a way that previous ones have not.

Part of it has to do with Park Geun-hye and her past, which is deeply entwined with South Korea’s recent, tumultuous history. The legacy of her father is still divisive. Supporters see him as saving South Korea from poverty and irrelevance by building up the economy from the rubble of the Korean war. Opponents say the economic development came at the expense of massive human rights abuses, including the torture and death of dissidents.