South Korea's president has taken sole blame for a "heartbreaking" scandal threatening her government and promised to accept a direct investigation into her actions amid rising suspicion that she allowed a mysterious confidante to manipulate power from the shadows.
In a high-stakes address to the nation in the capital Seoul, Park Geun-hye, her voice shaking, said the scandal was "all my fault and mistake".
And in an extraordinary moment, she also denied media speculation that she had been controlled by a religious cult.
"I feel a huge responsibility [for the scandal] deep in my heart," Ms Park said. "It is all my fault and mistake."
Her comments come at what may well prove to be the crucial moment of her presidency.
As calls for her to resign or be directly investigated rise, Ms Park is attempting to show the contrition and sense of responsibility that South Koreans demand while re-establishing her tarnished credibility.
She is in the fourth year of a single five-year term and, even before this scandal, faced criticism over the government's response to a ferry sinking that killed more than 300 and a perceived aloof nature.
One national poll had her approval rating at 5 per cent, the lowest for any modern South Korean leader.
"Anyone found by the current investigation to have done something wrong must be held responsible for what they have done, and I am also ready to face any responsibility," Ms Park said.
"If necessary, I'm determined to let prosecutors investigate me and accept an investigation by an independent counsel too."
Last week she surprised many when she acknowledged that she had relied on Choi Soon-sil, the daughter of a cult leader and Park mentor, for help editing presidential speeches and other undefined "public relations" issues.
Anger has exploded in the days since, with media reports claiming that the influence Ms Choi had went much deeper. There are reports that Ms Choi reviewed and made recommendations on government policy papers, helped choose presidential aides and even picked out Ms Park's wardrobe.
Thousands have protested, Ms Park has sacked many of her senior aides and is replacing her prime minister.
Ms Choi has been formally arrested and opposition MPs have demanded that prosecutors also investigate Ms Park.
The president's nominee for prime minister, the country's number two job, has suggested that Ms Park can be directly investigated, despite her immunity from prosecution.
Ms Choi (60) was arrested on Thursday as Seoul Central District Court accepted a prosecutors' request to issue a warrant citing alleged abuse of authority and fraud, according to court spokesman Shin Jae-hwan. She is being held in a detention centre.
In addition to the allegations Ms Choi was a behind-the-scenes influence on Ms Park, reports have claimed she pushed businesses to donate millions to two foundations that she controlled.
Ms Choi is the first person formally arrested in connection with the scandal. On Wednesday night, prosecutors detained one of Ms Park's former senior presidential secretaries after summoning him for alleged involvement in extracting £56.5 million in donations. Prosecutors have 48 hours to determine whether to request an arrest warrant for Ahn Jong-beom or release him.
Ms Park has fired eight presidential secretaries and nominated three new top cabinet officials including the prime minister in an effort to regain public confidence.
Opposition parties have described her personnel reshuffles as a tactic to divert attention from the scandal.
Ms Park may survive what has become the worse patch of an already rocky four years in office. But if her choice for prime minister is rejected and she is forced to name someone chosen by the opposition, it will hamstring her authority and may end her ability to govern.
Ms Park's choice for prime minister, Kim Byong-joon, said on Thursday that he thought it was possible to have Ms Park investigated, but added that the procedures and methods of any probe of the head of state must be handled carefully.
