A Japanese man who confessed to killing and dismembering the nine bodies police found in his apartment has been sent to prosecutors for further investigation.

Police say 27-year-old Takahiro Shiraishi is being questioned by Tokyo prosecutors Wednesday, a procedure before formal indictment.

Police arrested him Tuesday after finding nine dismembered bodies — eight of them female and one male — in cold-storage cases, covered with cat litter and hidden in his apartment in Zama, a city southwest of the capital. Shiraishi confessed to police that he tried to hide the evidence.

Police found the bodies while searching for a 23-year-old woman who had disappeared after exchanging Twitter messages with him. They are working to identify the victims, saying she might be among them.