BEIJING — When Hu Jintao, China's top leader, picked up the telephone last August to talk to a senior anticorruption official visiting Chongqing, special devices detected that he was being wiretapped — by local officials in that southwestern metropolis.
The discovery of that and other wiretapping led to an official investigation that helped topple Chongqing's charismatic leader, Bo Xilai, in a political cataclysm that has yet to reach a conclusion.
Until now, the downfall of Mr. Bo has been cast largely as a tale of a populist who pursued his own agenda too aggressively for some top leaders in Beijing and was brought down by accusations that his wife had arranged the murder of Neil Heywood, a British consultant, after a business dispute. But the hidden wiretapping, previously alluded to only in internal Communist Party accounts of the scandal, appears to have provided another compelling reason for party leaders to turn on Mr. Bo.
The story of how China’s president was monitored also shows the level of mistrust among leaders in the one-party state. To maintain control over society, leaders have embraced enhanced surveillance technology. But some have turned it on one another — repeating patterns of intrigue that go back to the beginnings of Communist rule.
“This society has bred mistrust and violence,” said Roderick MacFarquhar, a historian of Communist China’s elite-level machinations over the past half century. “Leaders know you have to watch your back because you never know who will put a knife in it.”
Nearly a dozen people with party ties, speaking anonymously for fear of retribution, confirmed the wiretapping, as well as a widespread program of bugging across Chongqing. But the party’s public version of Mr. Bo’s fall omits it.
The official narrative and much foreign attention has focused on the more easily grasped death of Mr. Heywood in November. When Mr. Bo’s police chief, Wang Lijun, was stripped of his job and feared being implicated in Bo family affairs, he fled to the United States Consulate in Chengdu, where he spoke mostly about Mr. Heywood’s death.
The murder account is pivotal to the scandal, providing Mr. Bo’s opponents with an unassailable reason to have him removed. But party insiders say the wiretapping was seen as a direct challenge to central authorities. It revealed to them just how far Mr. Bo, who is now being investigated for serious disciplinary violations, was prepared to go in his efforts to grasp greater power in China. That compounded suspicions that Mr. Bo could not be trusted with a top slot in the party, which is due to reshuffle its senior leadership positions this fall.
“Everyone across China is improving their systems for the purposes of maintaining stability,” said one official with a central government media outlet, referring to surveillance tactics. “But not everyone dares to monitor party central leaders.”
According to senior party members, including editors, academics and people with ties to the military, Mr. Bo’s eavesdropping operations began several years ago as part of a state-financed surveillance buildup, ostensibly for the purposes of fighting crime and maintaining local political stability.
The architect was Mr. Wang, a nationally decorated crime fighter who had worked under Mr. Bo in the northeast province of Liaoning. Together they installed “a comprehensive package bugging system covering telecommunications to the Internet,” according to the government media official.
One of several noted cybersecurity experts they enlisted was Fang Binxing, president of Beijing University of Posts and Telecommunications, who is often called the father of China’s “Great Firewall,” the nation’s vast Internet censorship system. Most recently, Mr. Fang advised the city on a new police information center using cloud-based computing, according to state media reports. Late last year, Mr. Wang was named a visiting professor at Mr. Fang’s university.
Together, Mr. Bo and Mr. Wang unleashed a drive to smash what they said were crime rings that controlled large portions of Chongqing’s economic life. In interviews, targets of the crackdown marveled at the scale and determination with which local police intercepted their communications.
“On the phone, we dared not mention Bo Xilai or Wang Lijun,” said Li Jun, a fugitive property developer who now lives in hiding abroad. Instead, he and fellow businessmen took to scribbling notes, removing their cellphone batteries and stocking up on unregistered SIM cards to thwart surveillance as the crackdown mounted, he said.
Li Zhuang, a lawyer from a powerfully connected Beijing law firm, recalled how some cousins of one client had presented him with a full stack of unregistered mobile phone SIM cards, warning him of local wiretapping. Despite these precautions, the Chongqing police ended up arresting Mr. Li on the outskirts of Beijing, about 900 miles away, after he called his client’s wife and arranged to visit her later that day at a hospital.
“They already were there lying in ambush,” Mr. Li said. He added that Wang Lijun, by reputation, was a “tapping freak.”
Political figures were targeted in addition to those suspected of being mobsters.
One political analyst with senior-level ties, citing information obtained from a colonel he recently dined with, said Mr. Bo had tried to tap the phones of virtually all high-ranking leaders who visited Chongqing in recent years, including Zhou Yongkang, the law-and-order czar who was said to have backed Mr. Bo as his potential successor.
“Bo wanted to be extremely clear about what leaders’ attitudes toward him were,” the analyst said.
In one other instance last year, two journalists said, operatives were caught intercepting a conversation between the office of Mr. Hu and Liu Guanglei, a top party law-and-order official whom Mr. Wang had replaced as police chief. Mr. Liu once served under Mr. Hu in the 1980s in Guizhou Province.
Perhaps more worrisome to Mr. Bo and Mr. Wang, however, was the increased scrutiny from the party’s Central Commission of Discipline Inspection, which by the beginning of 2012 had stationed up to four separate teams in Chongqing, two undercover, according to the political analyst, who cited Discipline Inspection sources.
Beyond making a routine inspection, it is not clear why the disciplinary official who telephoned Mr. Hu — Ma Wen, the minister of supervision — was in Chongqing. Her high-security land link to Mr. Hu from the state guesthouse in Chongqing was monitored on Mr. Bo’s orders. The topic of the call is unknown but was probably not vital. Most phones are so unsafe that important information is often conveyed only in person or in writing.
But Beijing was galled that Mr. Bo would wiretap Mr. Hu, whether intentionally or not, and turned central security and disciplinary investigators loose on his police chief, who bore the brunt of the scrutiny over the next couple of months.
“Bo wanted to push the responsibility onto Wang,” one senior party official said. “Wang couldn’t dare say it was Bo’s doing.”
Yet at some point well before fleeing Chongqing, Mr. Wang filed a pair of complaints to the inspection commission, the first anonymously and the second under his own name, according to a party academic with ties to Mr. Bo.
Both complaints said Mr. Bo had “opposed party central” authorities, including ordering the wiretapping of central leaders. The requests to investigate Mr. Bo were turned down at the time. Mr. Bo, who learned of the charges at a later point, told the academic shortly before his dismissal that he thought he could withstand Mr. Wang’s charges.
Mr. Wang is not believed to have discussed wiretapping at the United States Consulate. Instead, he focused on the less self-incriminating allegations of Mr. Bo’s wife’s arranging the killing of Mr. Heywood.
But tensions between the two men crested, sources said, when Mr. Bo found that Mr. Wang had also wiretapped him and his wife. After Mr. Wang was arrested in February, Mr. Bo detained Mr. Wang’s wiretapping specialist from Liaoning, a district police chief named Wang Pengfei.
Internal party accounts suggest that the party views the wiretapping as one of Mr. Bo’s most serious crimes. One preliminary indictment in mid-March accused Bo of damaging party unity by collecting evidence on other leaders.
Party officials, however, say it would be far too damaging to make the wiretapping public. When Mr. Bo is finally charged, wiretapping is not expected to be mentioned. “The things that can be publicized are the economic problems and the killing,” according to the senior official at the government media outlet. “That’s enough to decide the matter in public.”
Edward Wong contributed reporting.
This article, "Bo Xilai said to have spied on top China officials," first appeared in The New York Times.