The wife of China's former high-flying politician Bo Xilai is to go on trial charged with murdering British businessman Neil Heywood.
Gu Kailai, who is accused of poisoning Mr Heywood in November 2011, will be tried by a court in Hefei.
State media has called the case against her and an aide "substantial".
The country is preparing to install a new generation of leaders, and Bo Xilai had once been seen as a strong contender for one of the top jobs.
He was the Communist Party head in the city of Chongqing, where Mr Heywood died.
Some Chinese leaders are said to welcome the demise of such an openly ambitious colleague, but the case still needs careful handling for fear it might taint the Communist Party itself, the BBC's John Sudworth in Hefei reports.
Mr Heywood's body was found at a hotel in Chongqing, and the death was recorded as a heart attack at the time.
But four months later there was a dramatic twist, with Chonqing's former police chief Wang Lijun - once Mr Bo's right-hand man - fleeing to a US consulate to allege murder and a massive cover-up.
Ms Gu, a well-known 53-year-old lawyer, and her aide Zhang Xiaojun are now accused of killing Mr Heywood, who is said to have been a business associate.
State media said Ms Gu and her son Bo Guagua fell out with Mr Heywood over "economic interests" and that Ms Gu was worried about "Neil Heywood's threat to her son's personal security".
"The facts of the two defendants' crime are clear, and the evidence is irrefutable and substantial," a Xinhua news agency report said.
Ms Gu and her husband have not been seen in public since April, when the investigation was announced.
Bo Guagua, 24, is believed to be in the US after graduating from Harvard University.
"As I was cited as a motivating factor for the crimes accused of my mother, I have already submitted my witness statement," he wrote in an email to US broadcaster CNN on Wednesday.
"I hope that my mother will have the opportunity to review them," he wrote. "I have faith that facts will speak for themselves."
British diplomats will be allowed to witness the trial but journalists will not be attending. Ms Gu is being represented by state-appointed lawyers.
Discussion of the case has been very limited in Chinese media. In the week leading up to the trial, no reports have been observed in state press.
Comment also appears to be tightly controlled on the internet, with an increasing number of keywords related to the case apparently blocked.
Some microbloggers have appealed for a fair trial, amid a perception that Ms Gu's case may be linked to political manoeuvring.
Seven members of the politburo Standing Committee are due to retire later this year. Bo Xilai, now sacked from his official positions, had been tipped for the top until his fall from grace.
Dr Bo Zhiyue, of the National University of Singapore, believes China's leaders are keen to make the focus of the case criminal, rather than political.
''Bo Xilai is a controversial figure. The central leadership may be divided over how to handle Bo Xilai. I think they have some consensus over how to deal with Gu Kailai,'' he says.
He adds that there are signs she will be treated with a degree of leniency, pointing to the suggestion in state media that Ms Gu was in some way trying to protect her son.
Dr Jin Xiaopeng, a Beijing-based lawyer, told the BBC he believed that "due to Ms Gu's special status, the most she will get is a suspended death sentence".
It is not known whether Mr Bo will appear at the trial, or his former police chief Wang Lijun, whose flight to the US consulate in February - allegedly with information concerning the Heywood case - proved the catalyst for the scandal that engulfed Mr Bo and his wife.