The leader of the Kudo-kai major crime syndicate was served a fresh arrest warrant Tuesday for allegedly hiding hundreds of millions of yen collected from members affiliated with the group and evading income tax, police said.

It marks the first time the police have built a case against an organized crime figure for suspected violation of the income tax law by regarding dues collected from syndicate members as taxable income.

Satoru Nomura, the 68-year-old head of the Kitakyushu-based Kudo-kai, is already under indictment for the shooting death of a former local fishery cooperative leader in 1998 and attacks on a female nurse in 2013 and a dentist in 2014.

Three others were arrested Tuesday on suspicion of managing the dues, including Masakichi Yamanaka, a 64-year-old senior member of the group.

Nomura allegedly hid around ¥227 million collected in dues between 2010 and 2013 and evaded around ¥88 million in income tax, the police said.

Members affiliated with organized crime syndicates often collect protection money from restaurants and pachinko parlors operating on their turf as well as from drug dealers. The money is then handed over to their leaders as dues.

The police found that dues collected by the Kudo-kai had been wired to bank accounts held by Nomura’s relatives and others, prompting them to count the money as personal income, an investigative source said.

At a news conference in Kitakyushu, Naomasa Yoshida, chief of the Fukuoka Prefectural Police, described the Kudo-kai’s dues collection as an “antisocial” system that could motivate crimes.

“We estimate the dues to amount to hundreds of millions of yen a year, he said. “We will work to solve how the system works.”

With its members implicated in numerous shootings involving law-abiding citizens, the Kudo-kai has been designated by local public safety commissions as a particularly dangerous gangster group.