BEIJING >> The Communist Party has begun an investigation of a top aide to former President Hu Jintao, demonstrating the lengths to which President Xi Jinping is willing to go in his campaign to root out official corruption in China.

Xinhua, the state-run news agency, announced in a terse statement Monday that the official, Ling Jihua, was being investigated for "suspected serious discipline violations," the standard euphemism for allegations of corruption and abuses of power. It gave no further details.

Until his abrupt loss of influence in September 2012, Ling, 58, was a trusted aide to Hu, comparable to a White House chief of staff, and had been widely considered a candidate for promotion to the Politburo.

Steve Tsang, who studies Chinese politics at the China Policy Institute at the University of Nottingham, in England, said the investigation into Ling signaled that Xi was confident enough to expand his anti-corruption campaign to include senior associates of his predecessor.

"What it points to is that Xi will sustain the anti-corruption campaign and use it to strengthen his own position in the party and to make the party a more effective instrument of control, and for him to exercise that control," Tsang said in an email.

The investigation into Ling opens another chapter in a palace intrigue that began with a car crash two years ago that killed Ling’s 23-year-old son, Ling Gu, and critically injured two young women riding in the Ferrari he was driving on a Beijing ring road.

One of the women died a month later, and party insiders say the families of both women were later paid enormous sums to keep quiet.

According to party officials, Ling went to great lengths to cover up the death of his son, a graduate student at Peking University, and he continued to work as if nothing had happened. The scandal unfolded amid a once-in-a decade leadership transition and is thought to have contributed to a decision by Hu to relinquish his position as secretary of the Communist Party and chairman of the Chinese military, posts that his predecessor, Jiang Zemin, had retained into retirement.

Under the former president, Ling had directed the leadership’s nerve center, the General Office of the party’s Central Committee, but he was relegated to a less influential post ahead of schedule. He later failed to advance to the Politburo and lost his seat on the influential party secretariat.

His downfall on Monday came in the same manner as those of several other senior officials who have been recently toppled on corruption allegations: A tightening circle of investigations targets the official’s family and associates, and then the official is removed with a brief announcement from the party’s anti-corruption agency. The party’s investigation is usually followed by a criminal inquiry and a trial that ends in a guilty verdict and a prison sentence dealt out by a party-run court.

In Ling’s case, that termination was particularly precipitous. Just last week, he published an essay lauding Xi’s policies toward ethnic minorities in Qiushi (Seeking Truth), the party’s premier doctrinal journal. Ling said he was sure that "under the staunch leadership of the party center with Comrade Xi Jinping as general secretary," China’s Tibetans, Uighurs and other ethnic minorities would have a bright future.

But well before Monday, his brothers had been placed under investigation for graft and Ling’s own prospects appeared grim. In June, party investigators announced an inquiry into the activities of an older brother, Ling Zhengce, who was the deputy head of a government advisory body in the coal-rich northern province of Shanxi.

Xi and Wang Qishan, his political ally in charge of the party’s anti-corruption agency, the Central Commission for Discipline Inspection, have often said their drive against graft would catch both "tigers and flies," both senior and junior officials.

Ling did not reach the same high rank as other party figures taken down by corruption inquiries. But because he was still in power, his fall could signify that Xi is moving against senior sitting officials as he seeks to reshape the central leadership in his own mold, said Christopher K. Johnson, an expert on China at the Center for Strategic and International Studies in Washington, who formerly worked as a senior China analyst at the CIA.

"The tiger hunt is alive and well," Johnson said in emailed answers to questions. "It marks a fundamental inflection point in the anti-graft campaign whereby the target set at the tiger level is shifting from retired — if very senior — officials to sitting high-level officials. That opens the door to a whole new world of possibilities for the campaign."

Ling was often identified with a loose coterie of officials who rose through the party’s Communist Youth League, the organization previously led by Hu. Other standing officials associated with the Youth League network could also come under greater pressure and scrutiny, Johnson said.

"They understand that they remain the chief obstacle to Xi being able to place more of his associates on the next Politburo Standing Committee," he said. "That would seem to be the real game here."

The Ling brothers came from an official’s family in Shanxi. Their father, an ardent Communist, named his five children after party jargon: Zhengce means "policy," Jihua means "plan" and Wancheng "complete," and they have a brother Luxian ("line") and a sister Fangzhen ("guiding policy"), Gao Qinrong, a former Xinhua journalist from Shanxi who has followed the family’s rise and fall, said in an earlier interview.

Ling Jihua rose highest in the family. Under Hu, he became director of the party’s Central Committee General Office and head of the party leadership’s secretariat, posts that gave Ling great influence as a gatekeeper controlling access to Hu, who was succeeded by Xi.

As of late Monday, Ling had not been formally removed from his posts, and his name lingered as head of the United Front Work Department, the agency charged with managing the party’s relations with China’s ethnic minorities. But dismissal seemed only a matter of time.

Such was the ritual swiftness of Ling’s defenestration that within an hour of the announcement of the investigation, the China News Service issued a commentary declaring that his downfall showed that no official was immune to scrutiny.

"A party that dares to apply the knife to all corrupt elements, a party that dares to lance the abscess on its own flesh, is a party that can overwhelm all hardships without being overwhelmed by them," said the commentary, which was accompanied by what appeared to be a pseudonym, Guoping, that can be translated as State Commentary.

Andrew Wedeman, a professor of political science at Georgia State University who studies corruption in China, said Ling had come to embody the depravity of official malfeasance that flourished during Hu’s decade-long tenure.

"He is significant because of his position, but I think the real significance of the case derives from his connection to the kind of excesses of the Chinese nouveau riche under Hu Jintao," he said, adding that he thought Xi had little choice but to take down Ling.

"He’s treading a dangerous road, but I don’t know, if I’m Xi Jinping do I have an alternative?" Wedeman said. "If I stop this thing short I look like a coward, and I end up looking like my predecessors."

© 2014 The New York Times Company