Authorities in the central Chinese province of Hubei on Monday executed a mining tycoon, his brother, and three associates linked to a probe into former security czar Zhou Yongkang, official media reported.
Death sentences handed to Sichuan billionaire Liu Han, 48, his brother Liu Wei, Tang Xianbing, Zhang Donghua, and Tian Xianwei were carried out by the Xianning Intermediate People's Court after a review by the country's highest-level court, the Xinhua news agency said.
The executions, for participating in a "mafia-style organization," came after the Liu brothers and 34 others were found guilty of gang-related activities and murder last May.
Five others were handed suspended death sentences, while four got life jail terms and 22 others were jailed for varying lengths of time, it said.
The executions came suddenly, several months after the Hubei Provincial High People's Court rejected the five men's appeals, and amid widespread speculation over a possible last-minute reprieve by the Supreme People's Court in Beijing.
Political analysts have said that Chinese president Xi Jinping's anti-corruption campaign against high-ranking "tigers" and low-ranking "flies" has been highly politicized, and that those with friends in the right political camps are being protected from exposure.
Liu Han's sudden demise prompted suspicions that the government was seeking to limit damage to the reputation of the ruling Chinese Communist Party by killing off a key witness to the wrongdoing of officials not targeted in Xi's campaign.
"We know that Liu Han must have known a great deal of secrets," rights lawyer Sui Muqing said. "He was sentenced and executed in a big hurry."
"I think there is definitely a clear pattern here of silencing people," Sui said, pointing to what he called plenty of precedents in Chinese history.
"This has happened many times before in China, that important witnesses are killed off," he said.
Liu Han was found guilty of 13 crimes including murder, running illegal gambling establishments, and arms racketeering.
He denied most of the charges, including that of running a criminal gang, claiming his confessions were obtained through a combination of torture during interrogation and threats to his wife and child.
He shouted "I've been framed" and "I've been wronged" before being taken away by guards at the sentencing hearing, during which his younger brother, Liu Wei, also known as Liu Yong, was also sentenced.
The Liu brothers' personal assets were confiscated, while Liu Han's Sichuan Hanlong group was fined 300 million yuan (U.S. $48 million) for crimes including fraud in relation to bank loans.
According to Xinhua, Hanlong was judged to be a criminal organization, as it had an established hierarchy and regular members and profited from criminal activities.
With the collusion of government officials, Hanlong "illegally monopolized the gaming business" in Sichuan's Guanghan city, tyrannized local people and seriously harmed economic and social order, the agency said.
"The case was extremely vile and harmful," the Xianning Intermediate People's Court said in a statement on Monday.
According to the Supreme People's Court, Liu Han's activities were linked to eight deaths, gun sales, racketeering, vandalism, obstruction of official duties, disturbance of the peace, gambling, and harboring of criminals.
Liu Han was also responsible for Hanlong Group's loan racket and other "extremely harmful" monetary crimes, Xinhua cited the court as saying.
While China's tightly controlled state media have stopped short of linking Liu's case to that for former security czar Zhou Yongkang, Liu's rise coincided with Zhou's time as Sichuan party chief.
Reuters has reported that Liu was once a business associate of Zhou's eldest son, Zhou Bin.
On Dec. 5, Beijing announced Zhou's arrest following a probe begun in July by the Chinese Communist Party's disciplinary arm, the Central Commission for Discipline Inspection (CCDI).
Zhou, 71, has been accused of crimes ranging from accepting bribes to leaking state secrets and placed under a judicial probe.
Zhou's political and business empire spanned the mining and petrochemicals industries, a regional power base in Sichuan, and China's hugely powerful domestic security apparatus.
Many of his former political allies, business associates, and family members are also under investigation.
Xinhua quoted Zhou's successor at the party's Central Politics and Law Commission, Meng Jianzhu, as saying "criminal organizations" would be hunted down and eradicated under President Xi's anti-corruption campaign.
"We will target criminal organizations when they are small and allow them no room to regroup and re-emerge," Meng reportedly told a meeting in September.
"Officials who offer protection to criminal organizations will be hunted down mercilessly," he said.
A Sichuan-based journalist who declined to be named told RFA that his organization wouldn't be able to carry out any independent reporting into the Liu story.
"We will have to put out the Xinhua copy," the journalist said. "We don't dare carry out our own interviews or anything like that."
"This is very, very sensitive. We basically haven't been allowed to report on the Liu Han case at all."
Reported by Luo Bote and Lin Yuetong for RFA's Cantonese Service, and by RFA's Mandarin Service. Translated and written in English by Luisetta Mudie.