Park's longtime friend Choi Soon-Sil -- the daughter of her religious guru -- was vilified at the massive nationwide...
Park's longtime friend Choi Soon-Sil -- the daughter of her religious guru -- was vilified at the massive nationwide protests last year that rocked Asia's fourth-largest economy and led to Park's impeachment.
Choi was "the alpha and omega of the scandal", a prosecutor told the Seoul Central District Court, "the very person who created a national crisis which resulted in the country's first-ever impeachment of a president".
She "took advantage of presidential authorities to seek personal profit, undermined constitutional values and rattled the government system", he added. "Please sentence Choi to 25 years in prison."
He also sought fines and asset seizures totalling 126.2 billion won -- around $116 million.
The 61-year-old is accused of colluding with Park to extort millions of dollars from conglomerates, including South Korean giants Samsung and Hyundai, and using her connection with the president to meddle in state affairs.
Choi denies all 18 charges, including abuse of power, coercion and bribery.
The verdict is expected in January. If she is convicted the judges are not obliged to follow the prosecutors' sentencing request.
Choi, who wore a black jacket with a prison number pinned on her chest, bowed slightly to the judges before taking her seat next to her lawyers.
She showed no emotion as prosecutors reeled off the accusations against her, drinking water from from a cup or resting her chin on her hands.
But her defence lawyer Lee Kyung-Jae told the court: "25 years in prison? This would amount to telling the accused to die in prison."
And during a break Choi was heard screaming outside a side exit, prompting a short adjournment before she shuffled back into court, led by the arm by a guard and looking exhausted.
In a statement read to the court earlier, she said: "I always thought I should distance myself from the president but I failed to do so. I did not even realise I was being exploited by other people around me and now I am left wounded and alone."
Prosecutors also demanded a four-year prison sentence for the chairman of retail conglomerate Lotte Group, Shin Dong-Bin, and six years for a former presidential aide.
The scandal, one of the largest in South Korea's modern history, has exposed networks of privilege among the country's business and political elite and has seen a handful of officials and business leaders put behind bars.
Lee Jae-Yong -- heir to the world's largest smartphone maker -- began a five-year prison sentence in August for bribery, perjury and other charges relating to payments made by Samsung to Choi.
Lee was found him guilty of paying a total of 8.9 billion won ($7.9 million) in return for favours including government support for his succession at Samsung after his father was left bedridden by a heart attack in 2014. He is appealing the verdict.
Park was impeached in March and was taken into custody shortly afterwards.
Her own separate trial on multiple charges including abuse of power, coercion and bribery is continuing after the court extended her detention for six months in October, prompting her defence team to resign in protest.
It is unclear when a verdict might come in her marathon case, which has involved more than 100 witnesses.
But Thursday's request suggests prosecutors will demand a sentence of at least 25 years for her.
"It has been proved beyond any doubt that Choi and the former president colluded to take bribes," the prosecutor said Thursday.