Suspected serial killer Takahiro Shiraishi has been served a second murder warrant in connection with nine people whose bodies were found dismembered in his apartment in Kanagawa Prefecture.

The second warrant was issued over the slaying of Yokohama resident Kazumi Maruyama, 25, who disappeared on Oct. 18. Shiraishi, 27, allegedly killed Maruyama and stashed her body at his apartment in Zama. A cellphone believed to be hers was found in his room, investigative sources said.

Shiraishi, who has admitted to the slayings, was taken into custody in late October and arrested about three weeks later in connection with the slaying of Aiko Tamura, 23, who vanished on Oct. 23.

The case has sent shock waves across Japan.

Shiraishi is believed to have approached his victims online before luring them to his apartment. Although many of them had posted suicidal thoughts on Twitter and other social media sites, Shiraishi has told the police that none of them really wanted to die because they resisted his attacks, the sources said.

Eight of his victims were female and one was male. All were between the ages of 15 and 26. Their bodies were found chopped up and stored in coolers in his apartment.

Prosecutors are continuing to investigate what happened to the other seven, and additional murder charges are expected.