BEIJING (CNN) -- The wife of controversial Chinese politician Bo Xilai has been formally charged with murder, the state-run Xinhua news agency said Thursday.
She is Gu Kailai, suspected of killing British businessman Neil Heywood.
Her husband had been one of the country's most prominent politicians until he was sacked as the chief of Chongqing in what has been seen as a political power struggle.
Bo remains under house arrest and is under investigation for flouting Communist Party discipline.
"This was expected," said Joseph Fewsmith, an international relations professor at Boston University and a long-time China watcher, referring to the murder charges.
Chinese communist leaders are trying to settle the Bo Xilai matter before the party holds has its once-in-a-decade leadership transition at the Communist Party Congress meeting later this year.
Bo had been widely expected to rise to national leadership before his sudden fall from grace.
"There was a desire on the part of the Chinese Communist Party to get this case settled. It's not yet, but it is out of the party and into the hands of criminal courts -- well before the 18th Party Congress. We should expect a resolution of the Bo Xilai case within the next couple weeks," Fewsmith said.
"With these cases being dealt with at this time, I expect there to be smooth sailing to the 18th Party congress. There may be some bargaining to go, but most of it has been done."
Zhang Xiaojun, a family aide, was formally charged along with Gu. Chinese authorities announced that the two were arrested earlier this year on suspicion of intentional homicide and had been jailed.
Authorities say Gu and her son came into conflict with Heywood over "economic interests." They said she regarded Heywood as a threat to her son's safety. Gu and Zhang poisoned Heywood, authorities said.
The two are awaiting trial in Hefei, the capital of eastern China's Anhui province.
Fewsmith said the "one real surprise" is the allegation of a Heywood threat to the son.
"This had not previously been reported," he said.
A Bo family friend told CNN that Gu's legal team was appointed by the government, not the lawyers the family tried to hire for her. This friend asked not to be identified because of the sensitivity of the matter.
Heywood was found dead in a hotel in the southwestern Chinese metropolis of Chongqing in November. Initially, the cause of death was reportedly found to be excessive alcohol consumption, and his body was cremated without an autopsy.
In early February, Heywood's name was thrown into a media spotlight when Bo's former police chief, Wang Lijun, spectacularly sought refuge for a day inside a U.S. consulate.
Wang wanted political asylum, apparently fearing for his life and allegedly holding incriminating information against Bo. Media reports and online posts claim Wang clashed with Bo after suggesting the British man had been poisoned amid a business dispute with Bo's wife.
Britain asked China earlier this year to investigate the matter further after being informed of growing concern about Heywood's case.
"The details of the ongoing investigation are a matter for the Chinese authorities," a Foreign Office spokesman said in a statement Thursday. "However we are glad to see that the Chinese authorities are continuing with the investigation into the death of Neil Heywood. We are dedicated to seeking justice for him and his family and we will be following developments closely."
Speculation has been rife about the nature of Heywood's work in China and his ties to Bo's family.
Heywood had lived in China for more than a decade and was married to a Chinese woman. Among the companies Heywood advised was Hakluyt and Co., a consulting firm founded by former officers of the British spy agency MI6.
That link fueled rumors that Heywood might have had connections to British intelligence services.
But British Foreign Secretary William Hague denied that possibility.
"Mr. Heywood was not an employee of the British government in any capacity," he said in a letter.
Hague noted that government policy is usually "neither to confirm nor deny speculation of this sort."
But he said he was making an exception "given the intense interest in this case."