Gu Kailai is given a suspended death sentenced for the murder of Neil Heywood, and says in court that the judgment is fair. Source: Reuters Reuters

Gu Kailai, the wife of disgraced politician Bo Xilai, has escaped the death penalty for murdering British businessman Neil Heywood, a Chinese court announced on Monday.

A spokesman for Hefei intermediate court said that although the "despicable" crime deserved the death sentence, it would be suspended for two years because the Briton had verbally threatened her son and because Gu suffered mental impairments. This had weakened her self-control, although she had the ability to understand her actions and their result.

Suspended death sentences are almost always commuted to life imprisonment.

Tang Yigan, who is also the court's vice-president, added that the 53-year-old regretted her crime and had also provided information to investigations into other people's crimes.

According to his statement, she told the court: "The judgment is fair. It shows special respect to the law, to reality and to life."

A family aide, Zhang Xiaojun, was handed a nine-year jail sentence. Tang said it was relatively lenient because the 33-year-old was an accessory rather than the crime's instigator, had confessed and had expressed regret.

He Zhengsheng, a lawyer hired by relatives of Heywood to represent them at the hearing, said: "We respect the sentence from the court."

He said he had informed the Briton's family of the decision and thanked everyone for their concern.

Tang said the court believed Gu poisoned Heywood with cyanide after she and her son, Bo Guagua, had an economic dispute with Heywood in 2011.

Its investigation "confirmed Neil Heywood threatened Bo [Guagua] verbally, making the conflict worse, but [found] no proof he had encroached on Bo [Guagua]."

According to accounts of her trial, Gu's lawyers claimed Heywood had at one point locked Bo Guagua into a home in the UK.

Heywood's friends have said they do not believe he would have threatened Bo Guagua and fear he has been smeared to justify a lighter sentence for Gu.

The Briton's death last November in south-western Chongqing – where Gu's husband Bo was then party secretary – was initially ascribed to excessive alcohol consumption.

But the 41-year-old's death ultimately became the biggest political scandal in China for decades, only months ahead of a once-a-decade leadership transition.

Authorities said even before Gu's trial began that the evidence against her was irrefutable. But analysts suggest officials have faced a dilemma in sentencing her: too lenient a punishment might suggest that those connected to powerful leaders could literally get away with murder, while too heavy a penalty might be seen as retaliation against the family of a popular official by rivals.

"They didn't kill her. I think this is fair to her," said a friend of her family.

A witness from the courtroom said Gu looked calm as she heard the sentence and said she was willing to accept education and reform herself.

The defendants said they would not appeal. China's courts are controlled by the Communist party and experts say that the outcome of a case as sensitive as this one would have been decided at the highest levels.

Suspended death sentences have become more common in recent years, with official sources indicating they exceeded actual death sentences in 2007.

Joshua Rosenzweig, an independent human rights scholar in Hong Kong, said one study showed such sentences usually resulted in the criminals serving between 14 and 24 years, with an average of 18 years in prison.

Gu might also be eligible for medical parole, but would have to wait two years for her sentence to be commuted and then serve a minimum of seven more years.

Attention will turn to the fate of her husband, once tipped for a top leadership position. There has been no comment on Bo's case since the announcement this spring that he was being investigated for disciplinary violations and it is unclear whether he will face criminal charges or simply internal party measures. Some analysts think leaders may wish to wait until after the power transition before dealing with him.

Chongqing's former police chief Wang Lijun, who triggered the scandal when he fled to the US consulate in Chengdu after breaking with Bo, is expected to go on trial soon. It remains unclear what charges he will face.

In a statement, a spokesperson for the British embassy in Beijing said: "We welcome the fact that the Chinese authorities have investigated the death of Neil Heywood, and tried those they identified as responsible.

"We consistently made clear to the Chinese authorities that we wanted to see the trials in this case conform to international human rights standards and for the death penalty not to be applied.

"Our thoughts are with Mr Heywood's family during this distressing time. Consular officials have attended the trial to fulfil our consular responsibilities to the family and our focus remains on offering them all the support we can."

In a separate session held immediately after Gu and Zhang were sentenced, four police officers from Chongqing were jailed for covering up the murder.

Tang told reporters that the men knew Gu was the prime suspect but "faked, hid and destroyed" evidence so she would not face the law, with negative social consequences. Their actions led Heywood's relatives to agree to forego a postmortem.

The court heard all four had confessed. Guo Weiguo was sentenced to 11 years as he was the most responsible, while three others were jailed for between five and seven years as they had not destroyed key evidence when Guo asked them to do so. None will appeal.