Several members of the Kudo-kai crime syndicate have been arrested over the 2011 shooting of a man at a construction site in Kitakyushu, investigators said Friday.

The victim, in his 50s, was employed by Shimizu Corp., which had refused to pay money to the underworld group.

According to the police, the victim was shot in the abdomen with a pistol in Kokura-kita Ward shortly after 7 p.m. on Feb. 9, 2011.

The police are trying to determine whether Kudo-kai chief Satoru Nomura ordered the attack.

Nomura, 70, has been indicted in connection with several crimes, including the killing of the head of a local fisheries cooperative in 1998 and tax evasion involving about ¥319 million ($2.9 million) in income tax.

In and around Kitakyushu, attacks on construction companies that attempt to cut links with the yakuza stretch back more than 10 years, the police said.

A senior member of Kudo-kai claimed during his trial in May at the Fukuoka District Court that yakuza typically confiscate 1 to 3 percent of each contractor’s order volume in Kitakyushu.

The prosecutors said Kudo-kai collects several hundred million yen from the contractors each year and attacks people associated with firms that refuse to pay.

Gunmen have been attacking Shimizu-linked buildings, construction offices and business partners since 2006.

Nine months after the 2011 shooting, a 72 year-old man running a local contractor in Kitakyushu was shot dead.

The police arrested 12 Kudo-kai members in January in connection with that murder and prosecutors have since indicted eight of the men.