The Chinese government on Monday executed a former mining tycoon with links to the eldest son of disgraced security chief Zhou Yongkang, media reports said.

The High People’s Court in the province of Hubei ordered the execution of Liu Han, former chairman of the Sichuan Hanlong Group, who was found guilty of 13 charges including murder and illegal firearms sales. He was sentenced to death last May for murder and running a “mafia-style” gang along with 36 others.

Liu Han was executed along with his younger brother, Liu Wei, and three other associates, Tang Xianbing, Zhang Donghua, and Tian Xianwei, the South China Morning Post (SCMP) reported.

The case against Liu Han is reportedly one of the most prominent charges brought against a private businessman. Liu Han, who was in 2012 listed as China’s 148th richest person by Forbes, reportedly ran a criminal gang, responsible for the deaths of nine people. Police seized hand grenades, submachine guns, pistols and other firearms in a raid in 2013, the Guardian reported.

His case first attracted attention for a public murder in 2009 in Sichuan where three people were shot dead by gunmen at a teahouse. The suspects named Liu Wei as their affiliate, Xinhua reported. The attack was reportedly a gang hit against one of Liu Wei’s enemies.

That triggered a wide-ranging investigation that found the Liu brothers guilty of violating property development laws, embezzling money, organizing several murders, and illegal assaults and detentions. Their criminal activities had reportedly amassed 40 billion yuan ($6.4 billion) in assets.

Liu Han has been linked to Zhou Bin, eldest son of Zhou Yongkang, who was detained in December over allegations of accepting bribes. The elder Zhou had told Liu Han to look after and help his son, sources told SCMP.

Zhou Yongkang was stripped of his Communist Party membership in December after being accused of major violations of the party’s “political, organizational and confidentiality discipline,” accepting bribes, leaking state secrets, and giving favors to friends, family members, and mistresses. His activities reportedly caused heavy losses for state-owned assets. He is set to face prosecution.

Zhou Yongkang is the highest-ranking official targeted by President Xi Jinping’s major anti-corruption drive, which aims to crackdown on both “tigers” (high-profile party officials like Zhou) and “flies” (local, low-level officials) in an effort to clean up the country’s ruling party, China Daily reported.