Police investigating the June slaying of a family of four in Fukuoka have arrested a 25-year-old Chinese man on suspicion of violating the immigration law.
The man turned himself in Wednesday morning, saying he wanted to explain that he was not involved in the slayings, police said.
The man, from Liaoning Province, China, had been enrolled in the same computer school as another man, 23, who was arrested on an assault charge separate from the murder case. That man, who returned to China shortly after the slayings, is the key suspect in the murder.
Police allege that the 25-year-old man overstayed his visa and was working as a manager in an Internet cafe.
Clothing merchant Shinjiro Matsumoto, 41, his wife Chika, 40, their 11-year-old son Kai and 8-year-old daughter Hina were found dead June 20.
Police officials say the 25-year-old man has given obscure accounts on his whereabouts at the hours before and after the murder.
They are set to question the man further on his possible link to three other Chinese implicated in the case.