OSAKA -- A former gangster found dead last week just as Osaka police began investigating his suspected involvement in a series of shootings may have had money issues with one of the victims, investigation sources said Monday.

Kazuo Konoura, 57, who ran a money-lending business from his home in Sakai, Osaka Prefecture, is the main suspect in three separate shootings Wednesday night that left one person dead and two in critical condition. The fatality, 50-year-old pub manager Takeyoshi Kono, appears to have been one of Konoura's clients.

A document seized from Konoura's apartment, where he was found hanged in an apparent suicide one day after the shootings, appears to be a list of about 200 people to whom the ex-gang member lent money. Kono's name and address were included on the list. The list was kept in a safe at Konoura's house attached to a copy of a map of the area around Kono's pub in Izumiotsu.

Witness accounts of the shootings indicate they were the acts of a lone masked gunman. Konoura surfaced as a key suspect because one of the victims -- Chiemi Shimizu, a bar owner in Takaishi to whom he had been briefly married 20 years ago -- told police that she had been shot by her former husband.

Based on Shimizu's testimony, police had been preparing to obtain an arrest warrant for Konoura for the woman's attempted murder. Now that he is dead, police plan to send papers to prosecutors indicating him as the main suspect in her shooting.

Meanwhile, they continue to probe his suspected involvement in the other shootings.

Police have found in Konoura's room three .38 handguns as well as bullets that match the spent cartridges found at all three crime scenes.

Initially, Konoura did not seem to have links to any of the victims aside from Shimizu, but as the probe proceeded, investigators learned that Kono and Shimizu knew each other -- and Konoura was aware of their acquaintance.