Police will serve a murder warrant Monday on the 27-year-old man who allegedly killed nine people before dismembering and storing their bodies at his apartment near Tokyo, investigative sources said.

Takahiro Shiraishi was arrested on Oct. 31 on suspicion that he had disposed of one of the bodies at the apartment. With his detention period on the initial charge expiring Monday, police will serve a new warrant for killing one of the nine victims, Aiko Tamura, 23, the sources said Sunday.

Shiraishi confessed to the killings while in custody and the police later identified all nine victims whose bodies were discovered inside cooling boxes in the suspect's apartment in Zama, Kanagawa Prefecture. The body parts showed signs of being cut and some portions had reduced to bone.

The victims were eight women and a man aged between 15 and 26. According to police, after moving into the apartment in August Shiraishi used multiple Twitter accounts to contact people who had expressed suicidal thoughts, offering to help them die.

The unemployed Shiraishi said theft was a motive, and also admitted that he had lured some of the women with the intent to rape them.

The killings came to light in late October following a police search related to the disappearance of the Tamura, who was from Tokyo.