TOKYO - Japanese prosecutors on Thursday demanded capital punishment for the man dubbed the "Twitter killer" indicted over the 2017 serial murder of 9 people who had expressed suicidal thoughts on social media, a high-profile case that shocked the nation.

At a lay judge trial at the Tachikawa branch of the Tokyo District Court, prosecutors sought the death penalty for Takahiro Shiraishi, 30, who pleaded guilty to murdering, dismembering and storing the bodies of the 9 in his apartment near Tokyo.

"Nine young lives were taken in such a short period of 2 months," a prosecutor said, adding that his crimes "deserve death."

Prosecutors also pointed out that there was no way the victims consented to being killed based on Shiraishi's testimony that they resisted being strangled.

Throughout the trial, Shiraishi had said "there was no consent," but his defense lawyers argued that the accused killed the victims with their approval as they had expressed suicidal thoughts and that he is therefore guilty only of the lesser charge of homicide with consent.

Shiraishi said Wednesday he expects to receive the death penalty, adding, "I humbly admit my guilt and will accept the punishment."

The defense lawyers have also said Shiraishi was possibly either mentally incompetent or was in a state of diminished capacity at the time and should not be held criminally liable.

Before indicting him in September 2018, prosecutors concluded Shiraishi can be held criminally liable after 5 months of psychiatric tests.

According to the indictment, Shiraishi strangled and dismembered 8 women and a man aged 15 to 26 from Tokyo and 4 other prefectures from August to October of 2017. Their bodies were discovered inside containers such as cooling boxes in his apartment in Zama in Kanagawa Prefecture.

He is also alleged to have stolen cash from the victims and sexually assaulted all the women.