BEIJING (AP) -- Chinese lawmakers have stripped disgraced politician Bo Xilai of his last official position, formally expelling him from the country's top legislature and clearing the way for criminal proceedings against the once-rising political star.

Though largely a formality since Bo was purged from the Communist Party late last month, his expulsion from the congress on Friday removes his immunity from prosecution. That sets the stage for a criminal case involving accusations of corruption and other wrongdoing, including involvement in covering up the murder of a British businessman. Bo's wife and a household aide were convicted of the murder last month.

Moving swiftly, the top prosecutor's office announced that Bo has been placed under investigation for alleged crimes it did not specify. The brief statement said that the agency has imposed "coercive measures" on him, usually a euphemism for jail.

Chinese leaders are keen to resolve the party's most damaging public scandal in decades as they prepare for next month's once-in-a-decade transition of power. They are handing over to the next generation of leaders, who will be tasked with shoring up public support in the face of widespread disgust over official graft and influence peddling.

They may even want to push through a trial before the opening of the party congress on Nov. 8, though some experts say there may not be enough time. Leaders still need to reach a consensus on how harshly to punish Bo, which of his associates to include in the trial and ensure the accused remains compliant in the courtroom, said Ding Xueliang, an expert on the Chinese leadership at Hong Kong University of Science and Technology.

"It's really a very muddy situation," he said. 

As the most powerful official in the southwestern mega-city of Chongqing, Bo had been considered a candidate for a seat on the party's all-powerful Politburo Standing Committee, and his toppling exposed sharp infighting in the party's uppermost ranks.

The National People's Congress Standing Committee said it approved a decision to remove Bo as a deputy, but offered no details.

Bo's downfall has been spectacular: His wife, Gu Kailai, was convicted of murdering British businessman Neil Heywood, and Bo's former right-hand man was accused of taking bribes, abusing power and trying to defect to the United States, among other crimes.

Even before that, Bo had angered many in Beijing with his populist style that defied the authoritarian party's demands that those seeking higher office merely follow orders from Beijing and maintain a low-key image. Bo's initiatives included a sweeping crackdown on organized crime and a campaign to revive Mao-era songs and culture that reminded many of the excesses of the 1966-76 Cultural Revolution.

Bo's expulsion cements an impression of unity among the leadership in rejecting his neo-Maoist approach in favor of stability under the incoming slate of leaders, said China politics expert Feng Chongyi of the University of Technology in Sydney, Australia.

"It's very positive in that way, but not sufficient to conclude that the party will become any more liberal," Feng said.

Chinese authorities have not yet announced specific charges against Bo, but in expelling him on Sept. 28, the party accused him of offenses reaching back two decades that range from taking bribes and abusing his power to having improper relationships with an unspecified number of women. He has not been seen in public since mid-March and is believed to be in detention at a Beijing prison.

Beijing attorney Li Xiaolin said Thursday that Bo's wife's family has hired him and Shen Zhigeng to defend Bo, but the two lawyers are not yet formally accredited by the authorities to represent him.

Bo's downfall was set off when his former police chief and close confidant Wang Lijun fled to the U.S. Consulate in the southwestern city of Chengdu, where he revealed to diplomats details of Heywood's death, which previously was called accidental. A month later, Bo was sacked as Chongqing's Communist Party secretary and suspended from the 25-member Politburo.

The scandal raised talk of a political struggle involving Bo supporters intent on derailing succession plans calling for Vice President Xi Jinping to lead the party for the next decade, as well as concerns over corruption among top-tier politicians.

A lengthy New York Times expose published Friday claimed the family of Premier Wen Jiabao has amassed assets worth $2.7 billion through a web of investments, most of it accumulated after he rose to high office in 2002. Chinese censors swiftly blocked the Times' Chinese-language site, which carried a translated version of the story, although Internet users with the technical knowledge could still access it by penetrating China's firewall.

Chinese Foreign Ministry spokesman Hong Lei told reporters at a press briefing that the report "blackens China and has ulterior motives." He refused to elaborate despite several follow-up questions.

While Wen is expected to leave his post in the spring, the report is a blow to his reputation as a politician concerned with bettering the lives of ordinary Chinese.

In another example of the lack of transparency, a report released Thursday by the Washington think-tank the Brookings Institution points out that the brother of Vice Premier Li Keqiang has been a top official in the State Tobacco Monopoly Administration, even while Li oversaw public health policy.

The agency both regulates and runs the China National Tobacco Corporation, the world's biggest cigarette maker, and taxes on cigarettes are a significant source of government revenue.

With Li expected to be promoted to premier in the leadership change, the report suggests that the brother, Li Keming, should be reassigned.