Speculation that the 58-year-old would come under scrutiny by anti-corruption investigators had been rife for more than two years, and pundits were closely watching if Ling could survive the intense heat.

Last December, anti-corruption investigators had to act swiftly to detain him after receiving tip-offs that his wife was planning to flee the country, a source told the .

The turning point for the former rising political star came in 2012, with the death of his son Ling Gu, 23, in a Ferrari crash that also left two young women passengers badly injured. One later died unexpectedly in hospital after an injection, said.

The crash raised many eyebrows not only because of the whiff of corruption from the sports car the son was driving but also due to the father's attempts to cover it up.

Sources said he attempted to obscure the details of the accident with a media gag and fake the identity of the driver.

He also enlisted the help of the then-security chief Zhou Yongkang to cover up the accident, sources said. Zhou ordered police and paramilitary forces in Beijing to bring the situation under control and tried to conceal that Ling had mobilised the Central Security Bureau, responsible for party leaders' safety, to cordon off the area of the crash without authorisation.

Ling was also helped by Jiang Jiemin , the former chairman of the state-owned oil giant China National Petroleum Corporation, to pay off the families of the woman passengers in the car to ensure their silence.

A source said the car had been a gift from Taiyuan's detained former party chief Chen Chuanping. It had been bought by Taiyuan Iron & Steel Group, where Chen was chairman.

Andrew Wedeman, a professor of political science at Georgia State University, said the crash was " a particularly poignant symbol of corruption 'gone wild' among China's political elites."

Ling's move to cover up the scandal backfired. News of it spread among officials and it was subsequently exposed by the media, putting him in the hot seat.

This is probably why the said, in an editorial published yesterday, that Ling had ignored the power and influence of the internet, which was able to uncover any scandal.

"He seemed to strongly believe that his power enabled him to 'cover the sky with one hand' [fool the public], however… he didn't realise that he was under the close watch of the internet," the editorial said.

In person, Ling was a nondescript man of medium height and conservative appearance. He was low profile, hardworking and sources said he often stayed in his office burning the midnight oil.

But his appearance was in sharp contrast to his influence.

His main job was to serve the party leaders, overseeing their security, public appointments, public image, even medical care.

"Ling was the pivot who balanced various groups and the communications between them," said Zhang Lifan , the Beijing-based political commentator. "His role was like the chief palace eunuch Li Lianying to the Empress Dowager Cixi during the Qing dynasty," he said. "If you wanted to reach Hu, you had to get past Ling first."

An anonymous source close to the central government in Beijing said: "Leading the hub-like general office, he possessed power greater than any vice-premier."

Ling's rise through the ranks to the centre of power was actively promoted by Hu.

He spent years working in the Communist Youth League, Hu's power base. He later worked for Hu when Hu headed the secretariat of the Central Committee.

Ling was promoted to head the secretariat, the nerve centre of Zhongnanhai, five years after Hu became president.

"For a considerable time during Hu's term, Ling manipulated Hu," according to Zhang. "And it was Hu's inabilities that bloated Ling's power."

The news service Caixin once described Ling as a man who wielded "invisible power almost as great as members of the Politburo Standing Committee".

Kerry Brown, a professor at Sydney University who studies politics in the Communist Party, said Ling tried to avoid the limelight whenever he accompanied Hu on official trips and even told reporters not to mention him. Mainland media reports have recorded him saying "don't publicise me".

Ling was not only at the beating heart of government he was also reportedly the leader of a party clique.

In January this year, Xinhua made a rare acknowledgement of the factions within the Communist Party. Ling was widely seen as the head of the Shanxi gang.

It included many powerful politicians and businessmen originating from, or based in, the northern, coal-rich province. They included the former railway minister Liu Zhijun and Jin Daoming , the former vice-chairman of the standing committee of the Shanxi People's Congress.

By 2007, a secretive circle had emerged, according to the respected mainland investigative journalist Luo Changping. The group only accepted high-level cadres and a few businesspeople, all with Shanxi connections.

"The permission to [join] the circle's banquets meant someone could ascend to greater power," wrote Luo in a book about how he blew the whistle on Ling's ally, Liu Tienan , the former director of the National Energy Administration.

The circle was so secretive that even their members' secretaries or mistresses could not attend the events. Cadres met roughly every two months to enhance "friendship" in several luxurious clubs in Beijing. All of the core members of the secretive circle have been detained in corruption investigations.

In addition to his Shanxi fellows, Ling also built his political power base and amassed great wealth through his family members, including his two brothers, his wife, his nephew and many others.

His elder brother, Ling Zhengce became vice-chairman of Shanxi's top political advisory body when the younger Ling secured his place as top aide to Hu.

His younger brother Ling Wancheng started a business empire in the media and financial sectors. A former journalist, he set up a news website called Jiuzhou Online, later renamed Tiantian Online, the news service Caixin reported.

Ling Wancheng co-founded the Beijing Huijin Lifang Investment Management Centre in 2008 and became chief executive of a subsidiary called Huijin Lifang Capital, which became the centre's main investment body. Huijin Lifang made him a billionaire, according to the report. His wife Li Ping , a TV host, was detained last November by anti-corruption investigators.

Ling Jihua's wife Gu Liping, who tried to flee in December, was reportedly detained in Qingdao although there was no government confirmation. Media reports alleged Gu had used her business and NGOs as vehicles to receive bribes.

Ling's nephew Linghu Jian and his mother, Sun Shumin , established a series of advertising, public relations and exhibition companies between 2002 and 2005 with many called "Qiangshi", meaning "powerful", according to Caixin.

The companies boasted of their government ties and strong media relations. Sun had a stake in at least 10 companies, according to the report.

Sources said that Ling returned to work the day after his son's car crash. But his son's death was not the only thing weighing on his mind. For two years overseas media had been reporting scandals related to him and speculating whether he would be dethroned.

In December 2012, nine months after his son died, Ling moved out of his office in the Zhongnanhai compound to Fuyou Street in Beijing's Xicheng district, with a new title, Minister of the United Front Work Department.

Beset by rumours, Ling laid low, surfacing only to pen an article that some read as a final fightback, others as a last attempt to save his neck by appeasing President Xi Jinping .

Either way, it didn't work. Ling was detained a week after the article was published in , a party mouthpiece. Some say he woke from an afternoon nap in his office to find graft-busters at his door, then calmly put on a tie and jacket to meet his fate.

Wedeman said Ling Jihua's connections with other central and local cadres made his case "particularly interesting".

"To my mind, Ling is significant because he seems to be the embodiment of the excesses of high-level corruption that has developed over the past decade," he said.

The unravelling of Ling Jihua's career: timeline

Ling Jihua expelled from the Communist Party to face prosecution

Expelled from the Chinese People's Political Consultative Conference

Removed from the United Front Work Department

Investigated by anti-graft watchdog

Brother Ling Zhengce, vice-chairman of Shanxi province's political advisory body, investigated for graft

Ling becomes one of 23 deputy chairmen of the CPPCC, but receives the lowest number of votes

Ling made head of the United Front Work Department, secures seat on the Central Committee but his widely expected rise to Politburo falls through

Only son Ling Gu dies in a Ferrari crash

Ling serves as personal secretary to then-president Hu Jintao