Police on Sunday sent the chief guard at the Osaka Detention House and two gangsters to prosecutors over suspicions of bribery in 2004.
Katsuhiko Kuwano, 37, was arrested late Saturday on suspicion of taking bribes, while Seiki Kin, 66, boss of a gang affiliated with the Yamaguchi-gumi, and a senior member of the gang were arrested for allegedly offering the bribes.
Police on Sunday searched for evidence at related locations, including Kuwano's residence in Takarazuka, Hyogo Prefecture, and Kin's residence in Osaka.
Kin allegedly paid travel and entertainment expenses to the tune of 200,000 yen for Kuwano and his family in July and August 2004, and Kuwano also received an automobile from the gangster that October, according to police officials.
Kuwano is believed to have received the bribes in exchange for doing favors for Kin while the gang boss was at the detention house in Miyakojima Ward following his arrest on suspicion of attempted extortion, they said.
According to investigations, Kuwano changed the gangster's cell at his request. Other favors were apparently in connection with Kin's correspondence or meeting with people from the outside.