He was poisoned last November in a hotel room in the mega-city of Chongqing by a henchman of city party leader Mr Bo, using a lethal dose of potassium cyanide - a poison that kills within minutes in tiny doses, according to the claims.
A single teaspoon of potassium cyanide is 50 times the fatal dose and shuts down body cells, rendering victims unconscious in ten to 20 seconds and dead within minutes, leaving the appearance of death by cardiac arrest.
A city official has allegedly confessed that he prepared the poison and handed it to an employee of Mr Bo, who administered it to Mr Heywood on the party chief's instructions, according to the accounts.
It is not known how the poison was given to Mr Heywood - who is understood to have lain dead for up to 36 hours before being discovered by a hotel cleaner - but a tiny drop put into a drink would have been enough to kill him.
Then - in a scene worthy of a thriller - Mrs Gu, 53, is said to have wept as she met with Mr Heywood's wife Wang Lulu in a cafe two days after the murder and begged her to agree to have her husband quickly cremated.
Police chief Wang Lijun, who later turned whistleblower and fled to a US consulate seeking asylum, allegedly ordered his officers to record Mr Heywood's death as a heart attack. Bo had those officers who refused to do so imprisoned and tortured, according to the blog accounts.
In the latest twist, it now appears that Bo's playboy son Bo Guagua may be seeking asylum in the US. According to reports, he has left his Boston home with a police escort after a group of Chinese men were seen watching his flat.
What appears to be the inside story of the biggest political crisis in China since the 1989 Tiananmen Square massacre emerged yesterday on suppressed internet sites linked to Chinese dissidents, four days after Beijing announced that Bo had been officially ejected from the ruling Politburo.
That same announcement revealed that Mr Bo's wife Gu and family employee Zhang Xiaojun had been arrested and were "highly suspected" of the murder of Mr Heywood, although it gave no details of how he was killed.
Since the scandal broke, China has routinely suppressed accounts of it, with search engines frozen and pages blocked whenever anyone tried to seek out details of the key players. But yesterday, the country's censors appeared to be turning a blind eye and allowing the descriptions of Mr Heywood's murder and the sex-and-money scandals that allegedly led to it to circulate widely.
The move - suggesting the government is encouraging or even planting stories about the Heywood affair - implies that the accounts are officially sanctioned, or that officials are intent on spreading black propaganda to crush any residual support for Mr Bo.
However, sources close to the situation say that internet rumours so far have been "95 per cent accurate".
Many of the key claims over the scandal circulating on the internet in China - including Mr Bo ordering the killing, the way Mr Heywood was poisoned, the huge transfers of money overseas and the previous crimes and affairs of Mr Bo - originate from the US-based anti-Communist Boxun website, which is routinely blocked within China.
However, Boxun's articles are frequently recirculated on micro-blogs within China, which themselves are closely monitored by Communist Party censors and shut down when they relay information considered too sensitive.
Last night, the unconfirmed accounts of Heywood's murder were continuing to run on a variety of reputable and widely-read websites within China, including a major legal site and the political website chinathinktank.cn.
Charismatic 62-year-old Mr Bo's political career was effectively brought to a close with Tuesday's announcement of his suspension and his wife's arrest over Mr Heywood's murder.
A month earlier, he was deposed as Chongqing party leader after police chief Wang fled to the US consulate in Chengdu, seeking asylum and implicating Mr Bo and his wife in the crime.
The family of Mr Heywood, a suave middle-class Englishman who became close to one of China's top political dynasties, was originally told he had died of a heart attack triggered by excessive drinking, despite the fact he rarely touched alcohol.
Father-of-two Mr Heywood met Mr Bo when he was mayor of the north-east city of Dalian in the Nineties and became an unlikely confidante, mentoring Mr Bo's indulged son Bo Guagua and helping him get a place at his alma mater, Harrow.
Mr Heywood is then believed to have helped manage the family's finances as Mr Bo moved to jobs in Beijing then Chongqing, but fell out with Bo's wife Gu in 2010 when she became paranoid over anti- corruption investigations into her family's finances.
Their relationship disintegrated when Mrs Gu reportedly asked Heywood to swear allegiance to the Bo family and divorce his Chinese-born wife Wang Lulu, who is now reported to be desperate to flee China. Mr Heywood refused and, fearing for his safety, considered taking wife, son and daughter back to Britain. Then, in November, he was summoned to a meeting with the Bo family in Chongqing and ended up dead in a hotel room, having earlier reportedly told a friend he had lodged details of the Bo family finances with a lawyer in Britain as a security.
Despite his downfall, Mr Bo remains hugely popular in Chongqing and Dalian - the cities he treated as personal fiefdoms - where many supporters believe Mr Heywood's murder and Mrs Gu's arrest are an elaborate set-up by his political enemies.
There were false rumours of an attempted coup in Beijing by his allies when he was ousted as Chongqing leader in March, and China's leaders remain desperate to quell party infighting ahead of a once- in-a-decade leadership switch this autumn, giving them a strong incentive to discredit Bo.
If true, however, the accounts circulating on China's internet yesterday expose an astonishing scandal engulfing a man who, until recently, expected to step up to the elite nine-member Politburo Standing Committee in the autumn reshuffle. They also raise the possibility that Mr Bo, who despite being ousted and held under effective house arrest has not so far been accused of any crime, may soon be charged with involvement in Mr Heywood's murder, a crime that carries the death penalty in China.
One account claims Mr Bo was a philanderer who slept with more than 100 women, including TV presenters and models, during his time as Dalian mayor from 1993 to 2000.
Billionaire chemical tycoon Xu Ming - a supporter of Mr Bo who is now also under investigation - is alleged to have sought out young women for Mr Bo to sleep with, according to the account.
Mr Bo's former police chief Wang Lijun is said to have secretly videoed Bo with some of his lovers when his philandering continued in Chongqing, and to have compiled a dossier of evidence against him that he handed over to the US consulate in Chengdu in February.
The account described Mr Bo as being "drunk with power and in thrall to his own personality cult, regarding himself as behind only the first Chinese emperor Qin Shihuang and Mao Zedong as the greatest man in Chinese history".
It alleges that Mr Bo and his wife Gu had been involved in the murder of a number of other people in Dalian and Chongqing, and claimed Mr Bo had received the equivalent of nearly £100 million ($192 million NZD) in bribes during his time in Chongqing alone.
A separate, online account containing a number of the same key facts alleges that Mr Heywood was responsible for transferring eight billion yuan ($1.5 billion NZD) in assets to overseas accounts on Mrs Gu's behalf.
Describing Mr Heywood's poisoning, the account says a hotel- room attendant found his body on November 14. "Several policemen were involved in the case," the account said, adding: "Wang Lijun asked them to write 'heart attack' in the report. The police refused. Wang Lijun told Bo Xilai this. Bo was furious and put the police who refused into prison and tortured them."
Describing the meeting between Mr Gu and Mr Heywood's wife Wang Lulu at a Chongqing cafe two days after the murder, the account says: "Police cleared the cafe and stood armed outside the door. Gu wept. Eventually, Wang Lulu agreed they would not do an autopsy and accepted the conclusion that he had died from excessive drinking and to the cremation of the body."
Accounts say a British diplomat, along with two Chinese policemen, attended Mr Heywood's cremation in Chongqing.
The heightened speculation over the murder will renew the anguish for Mr Heywood's wife and children, who live in a gated residential compound north of Beijing, where rent is £3,000 a month upwards.
Mr Heywood's work for the Bo family is believed to have at least partly funded his comfortable lifestyle. Both children attend British-run Dulwich College in Beijing, where annual fees are about £20,000 per child.
The scandal comes just months before a new president and premier take power in China, a process that takes places in stages from October onwards and which the Communist Party wants to be smooth and orderly.
Mr Bo's fall, however, has triggered the most intense in-fighting in decades as his former allies are sidelined and rival candidates jostle for the seat Mr Bo was expected to take on the Politburo Standing Committee that effectively runs China.
The downfall of Mr Bo and the arrest of his wife have meanwhile left China on edge, with many people convinced he is the victim of a set-up and supporters in Dalian and Chongqing braced for a feared round-up of his former comrades.
When rush-hour traffic ground to a halt in Dalian on Friday afternoon, rumours swept the city that investigators from Beijing had sealed off roads to arrest business associates of the disgraced former mayor.
"Whenever someone gets too popular in China, the government finds a way of bringing him down," a taxi driver said. And a teacher who has worked in Dalian for four years said: "Everyone thinks the government was behind this. They wanted to cut down the tall poppy."
Advertising executive Qiu Tian, 37, said: "Bo was arrogant and made a lot of enemies. But he did a lot of good for Dalian and we miss him."
Online forums also reflect an instinctive suspicion of the official line on Mr Heywood's death.
"This is nothing to do with getting justice for the Englishman's family," one person wrote.
"It's about making sure the political career of Bo Xilai is dead."
1 THE OLD HARROVIAN
Jaguar-loving, chain-smoking Old Harrovian businessman Neil Heywood, an international relations graduate, went to China in the early Nineties, initially to study Mandarin. He then began teaching English in the seaport of Dalian in North-East China where he met the then mayor, Bo Xilai, after offering to promote the area. According to the latest accounts, Bo's wife Gu Kailai introduced Mr Heywood to his future wife Wang Lulu.
2 THE STAR POLITICIAN AND HIS AMBITIOUS WIFE
Charismatic politician Bo and his wife Gu, a Peking university graduate and a formidable lawyer, were rising stars in the Chinese hierarchy, sometimes described as the "Jack and Jackie Kennedy of China" with Bo tipped to join the top ranks of the Communist party before he was sacked as local leader last month. According to new accounts, Heywood began an affair with Gu and helped her to spirit nearly £800 million in assets out of China. In 2010, he told friends he feared for his life after falling out with the family.
3 THE SON WHO BECOME A PLAYBOY
Mr Heywood is said to have helped ease Bo and Gu's son Bo Guanga - who began his English education aged 12 in a Berkshire prep school - into his own alma mater, Harrow. In 2006, Bo Guanga went to Balliol College, Oxford, where he was suspended in his second year and graduated a year late.
Contemporaries say Bo Guanga, pictured above with friends, gained a reputation at Oxford as a playboy who loved fast cars and women. He now attends Harvard University in the US.
4 HEYWOOD'S CHINESE BRIDE
Neil Heywood and his family - wife Wang Lulu, right, and their children Olivia, 11, and Peter, seven - set up home in a three-storey house, above, in a gated community in Beijing, where rents can be £3,000 a month. Gu is said to have been godmother to the children, who go to Beijing's Dulwich College, with fees of £20,000 a year.
5 HEYWOOD'S HOTEL RENDEVOUZ
In February this year, Bo's police chief Wang Lijun fled to the US consulate and asked for asylum.
According to the latest accounts, he was involved in covering up Mr Heywood's murder, presenting the death as a heart attack, before turning whistleblower and handing over a dossier of evidence. The British Embassy repeatedly urged the Chinese authorities to investigate Mr Heywood's death.
6 THE WHISTLE BLOWING CHIEF
On November 14, 2011, the body of Mr Heywood was found by a cleaner in a Chongqing hotel room, such as that pictured right. He was cremated without a post-mortem after a coroner declared he died of a heart attack. He had reportedly flown to Chongqing, pictured left, from Beijing for a meeting with Bo and his family. A British diplomat and two Chinese policemen are reported to have attended his cremation.
7 THE HERD KILLER
Shockingly, latest accounts claim Heywood was poisoned by a henchman of Bo who used a lethal dose of potassium cyanide - a poison that kills within minutes in tiny doses, leaving the appearance of death by cardiac arrest. A city official has allegedly admitted to preparing the poison and handing it to an employee, who administered it to Mr Heywood on Bo's orders.
- Daily Mail
