Police said Monday they have identified one of the nine dismembered bodies found at an apartment near Tokyo and plan to serve a warrant for murder against the man they arrested last week.

The police said Aiko Tamura, 23, from the Tokyo suburb of Hachioji was the first victim to be identified through DNA analysis. The suspect Takahiro Shiraishi, 27, who has admitted to killing the nine, was arrested last Tuesday on suspicion of dumping one unidentified body.

Suspect used Twitter account "hangingpro" to contact suicide wishers

9 dismembered bodies found in man's apartment near Tokyo

DNA samples taken from Tamura's toothbrush and a body recovered from a cooling box in the apartment in Zama matched, according to the police.

Investigative sources said the remaining eight could be a man and seven women -- a couple thought to be around 20, three high school girls, one university student and two other women.

They are from areas around Tokyo and Fukushima, northeastern Japan, and some are believed to have expressed suicidal thoughts on Twitter.

Following the murder case, the Japanese unit of Twitter Inc. said it introduced new rules to ban users encouraging or promoting suicide and other acts of self-harm.

Tamura was last seen on security cameras walking with Shiraishi in railway stations in Hachioji and Zama, Kanagawa Prefecture, on Oct. 23. The police also found a bag believed to be the victim's in his apartment in Zama.

Among the evidence collected at Shiraishi's apartment are various cards, including a bank card, which may have belonged to the victims, investigators said. They are also scouring missing person databases to identify the eight remaining unknown victims.

Shiraishi was quoted by police as saying that he had temporarily stored bodies in a refrigerator as "in the case of the first and second victims I could not dismember the bodies in one day." The police have detected traces of blood in the fridge.

The suspect confessed to killing the first victim, believed to be the female half of the Kanagawa couple, at his apartment in late August, days after moving there on Aug. 22.

Shiraishi added that he made her transfer 500,000 yen (about $4,400) to his bank account in advance to "cover the expense of moving in." The police suspect Shiraishi had rented the room strictly for the purpose of committing murders.

As the suspect has told investigators he "wanted an easy life," the police suspect the murders were partly motivated by money.

A woman, who said she repeatedly contacted Shiraishi before the series of crimes surfaced, told Kyodo News that the suspect had demanded all of her assets in exchange for killing her.

The police also discovered a saw, knife, scissors and goggles in his room. A replacement blade for the saw has also been found, leading them to suspect the tool has been repeatedly used to dismember the bodies.