“Under conditions where her mental state is abnormal, the investigators put her under immense pressure to expose me,” Bo said.

The lurid details have a serious political side, with the ruling Communist Party using the trial against Bo, a former Politburo member and party leader of the megacity of Chongqing, to cap a messy political scandal unleashed by suspicions that his wife killed a British businessman.

That scandal led to Bo’s political ouster, cemented by criminal charges of interfering with the murder investigation and netting US $4.3 million through corruption. The trial is widely believed to have a predetermined outcome — conviction — but Bo has mounted an unexpectedly spirited defense.

The proceedings are lasting longer than other recent high-profile trials, including the August 2012 conviction of Gu in the murder of a British businessman and the corruption conviction in June of a former railways minister. In those cases, the defendants pleaded guilty in daylong proceedings and scant details were released.

Bo’s trial had been expected to be similarly swift, but observers say he may have negotiated for his day in court. “It’s most likely that Bo has made concessions to the disciplinary commission to win a chance to defend himself in the trial,” said veteran lawyer Zhang Sizhi, who has represented many defendants in high-profile political cases, including Mao Zedong’s wife in 1980.

The trial has focused attention on Bo’s alleged economic and official misdeeds and avoided discussing the political battle he’s widely perceived as having lost in his pursuit of a seat in China’s apex of power ahead of last year’s leadership transition.

That political context means a guilty verdict is a foregone conclusion, analysts say, and giving Bo a chance to defend himself adds credibility to the process.

“He is being allowed to show a degree of defiance, and as long as he does not actually challenge the actual authority and legitimacy of the leadership in putting him in the dock on political grounds, it’s not going to change anything,” said Steve Tsang, a China expert at the University of Nottingham. “It just makes the leadership look better that Bo Xilai had a ‘fair’ trial.”

Courtroom revelations by the prosecution have laid bare the way that shady ties between powerful officials and businessmen can play out in China, as well as the extents to which a political family might go to hide its wealth. Part of the couple’s influence comes from their pedigree as the children of revolutionary veterans, a status that gives them access to important political and business networks.

Prosecutors depicted Bo as trading favors with Xu Ming, a businessman in the northeastern city of Dalian, where Bo was a top official. Bo, they said, acted as Xu’s political patron, helping the businessman take over a football club and secure land for a hot-air balloon project in return for expensive gifts for the family that included a villa in France.

In presenting part of Gu’s testimony in a video, the court also provided the first visuals of the woman since she was convicted of murder last year.

Speaking softly but apparently at ease, Gu said Xu gave the family the villa, paid for their international air tickets and bought expensive gifts for them, including a Segway — an electric standup scooter — for her son. All this, she said, was done with Bo’s knowledge.

“Xu Ming is our old and longtime friend,” Gu is seen telling her questioner. “We had a very good impression of him and believed he was honest and kind, so we trusted him a lot.”

Details of the trial are being filtered through transcripts provided by the court on microblog sites, giving a rare but possibly incomplete window into proceedings that the public and foreign media have been barred from attending. Outside the courthouse, security has been tight, with main roads and a flyover sealed off to traffic and crowds kept far away. The trial wrapped up bribery allegations Friday and moved on to hear the charge of embezzlement in proceedings that will continue Saturday.

In defending himself, Bo has focused on recanting earlier confessions, challenging the relevance of evidence presented and stating he was ignorant of any favors that two businessmen were providing his wife and son. He described the testimony presented by his wife and the businessman Xu as “fabricated,” and that of his former police chief Wang Lijun as “tittle-tattle.”

Besides the testimony, prosecutors have presented documents — receipts, copies of faxes, government approvals — and photos of the villa they say prove the businessman helped enrich the Bo family in return for political favors from Bo. They have said their witness testimonies were obtained legally and that Gu, in particular, was not affected by any medication that would impair her self-control.

In a written statement, Gu detailed how she and some associates hatched a plan to set up a property company to buy the villa to evade taxes and hide the family’s ownership of it. Gu said the villa was to be refurbished and rented out as an investment to ensure a steady income for her son, Bo Guagua, who was studying in Britain at the time.

Prosecutors said Xu’s company paid hundreds of thousands of dollars on travel expenses for Gu, their son, friends and relatives over the past decade. They included the son’s vacations in countries such as France and Cuba, and a tour of Africa.