Hong Kong (CNN) -- The disgraced politician at the center of China's biggest political scandal in years has been linked to a criminal act for the first time since he was removed from office, the state-run Xinhua news agency has reported.
Bo Xilai, who was head of the Communist Party in the southwestern city of Chongqing and once seen as a future president, was reportedly warned by his former right-hand man that his wife was suspected of murder.
The revelation came during this week's trial of Wang Lijun, Bo's former police chief and vice mayor in Chongqing.
In the first official account of the two-day hearing, the court was told that Wang was "angrily rebuked" and slapped on the face by Bo -- who the report referred to as the major official in charge of Chongqing's municipal party committee -- when he revealed his suspicions, Xinhua said.
Wang was on trial charged with abuse of power, defection and bribe-taking. The case, which precipitated Bo's downfall, began after Wang arrived at the U.S. consulate in the nearby city of Chengdu one evening in February in an apparent asylum attempt.
During a frenzied 24 hours, he reportedly revealed to U.S. officials a jaw-dropping tale of corruption and murder involving his boss. Wang was later collected by central government authorities and disappeared from the public eye.
According to Thursday's Xinhua report, Guo Weiguo, a former high-ranking police official, heard the exchange between the two men on January 28 this year. He told police: "Once Wang was slapped, the hostility between Wang and Bo came out into the open."
Bo's wife, Gu Kailai, was found guilty of murder in the death of a British businessman Neil Heywood last month. Chinese authorities reported that Gu and her son had "conflicts" with Heywood "over economic interests."
Prosecutors at his trial allege Wang knew Gu was involved in the murder of Heywood last November but covered up for her. But this relationship became increasingly strained as Wang became concerned by the number of people who became aware of the murder case. In his confession, Wang described how Gu became hostile "and began to guard herself against me," Xinhua said.
Bo had been an influential and controversial member of the Communist Party's politburo, the elite group of 25 men who run China.
Appointed to the top job in Chongqing in 2007, Wang was assigned to lead his crime-fighting program.
Under Wang, the "da hei" or smash black campaign reportedly caught nearly 3,000 criminal groups and detained thousands of suspects. It also led to the execution of notorious figures in the city's underworld.
The crackdown, along with economic reforms in the city of more than 30 million, helped burnish the political credentials of Bo, who aspired for a spot in the Party's Standing Committee of the Politburo, a nine-member body that effectively rules China.
But Wang's heavy-handed, crime-busting methods were decried as brutal by critics.
Bo's red-tinged economic policies -- which have included millions spent on social housing -- garnered him a rock star status in Chongqing but in Beijing, some party chiefs were taking a different view.
His populist policies and high-profile personal style were seen as a challenge to the economically liberal and reform-oriented faction within the Chinese Communist Party (CCP).
The political divisions came to a boil in March when China's national legislature convened its annual meeting in Beijing.
Speaking to reporters on March 9 on the sidelines of a panel discussion of Chongqing delegates, Bo defended his policies. "Ask any citizen on the street if they support fighting corruption and they'll say 'yes'," he boomed. Addressing the rich-poor divide, he said: ''If only a few people are rich then we are capitalists, we've failed."
That may have been Bo's last stand.
On March 14, Premier Wen Jiabao obliquely reprimanded Chongqing's leadership over the Wang incident during the premier's annual press conference. Wen also referred to the damage wrought by the Cultural Revolution -- a reference that alluded to Bo's red revival in Chongqing -- and said that the city's stellar double-digit economic performance had been the fruits of several administrations and not just Bo's work alone.
The following day, Bo was sacked and stripped of his political office due to an unspecified "serious breach of party regulations." The Party still hasn't revealed what those regulations are. But until the trial of Wang, there had been no suggestion Bo had been aware of his wife's actions before her arrest and conviction for murder.
CNN's Steven Jiang, Jaime FlorCruz and Dayu Zhang contributed to this report.