China sentenced the wife of fallen Politburo member Bo Xilai to death yesterday but suspended her execution, setting the stage for a possible final purge of Bo himself in a scandal that has shaken Beijing ahead of a leadership transition.

The sentence means Gu Kailai is likely to face life in jail for murdering British businessman Neil Heywood last year.

It also brings a curtain down on China's most sensational trial in three decades, yet opens a new and more politically dangerous act for the ruling Communist Party – how to deal with Mr Bo, an ambitious and well-connected provincial leader whose downfall exposed rifts in the party.

"I feel the verdict is just and fully reflects the court's special respect for the law, its special respect for reality and, in particular, its special respect for life," Gu said of the sentence in official television footage of the hearing.

Gu, 53, wore a white shirt and black suit and stood expressionless, hands folded in front of her, as she spoke, pausing at one point to find the right words.

At her trial on August 9, Gu admitted poisoning Mr Heywood last November, and alleged a business dispute between them led him to threaten her son, Bo Guagua, according to official accounts from state media.

A court official, Tang Yigan, said the court had concluded Mr Heywood used threatening words against Bo Guagua, but had never acted on them. The court also found Gu's actions reflected a "psychological impairment" but it did not elaborate.

Gu could still face execution if she commits a new offence in the next two years. Almost invariably in China, however, such suspended sentences are commuted to long prison terms. The court, in the eastern city of Hefei, also said Zhang Xiaojun, an aide to the Bo family, was sentenced to nine years in jail for acting as an accomplice to the poisoning.

"With both of the defendants declining to appeal, this marks the end of things," said Zhang's lawyer, Li Renting.

Four policemen were also convicted yesterday of having sought to protect Gu from investigation, receiving jail sentences of between five and 11 years – a development that could prove damaging for Mr Bo because it establishes formally there was an attempted cover-up.

Police sources in Chongqing, the south-western municipality ruled by Mr Bo until he was ousted as its party chief in March, have said Mr Bo tried to shut down the investigation into his wife after being told early this year she was a suspect.

Some Chinese political experts doubt the party will look to prosecute Mr Bo, and note his name was not cited at either the trial of his wife or the four policemen.

However, He Weifang, a law professor at Beijing University, said he believed Mr Bo would still face a court once the party had decided how to handle him.

"I don't think we can say that Bo Xilai has been cut free from this," he said.