A Japanese court finalized on Tuesday a death penalty ruling given to the man dubbed Japan's "Twitter killer" after he withdrew an appeal filed by his lawyers in the case related to the 2017 serial murders of nine people who posted suicidal thoughts on social media.

The defense team for Takahiro Shiraishi, 30, appealed the death sentence on Dec. 18 last year, but he canceled the procedure three days later, according to the Tachikawa branch of the Tokyo District Court, which found him guilty of murdering, dismembering and storing the bodies of the nine in his apartment near Tokyo.

Flowers and drinks are seen on Nov. 20, 2017 on a street near the apartment complex in Zama, near Tokyo, where nine dismembered bodies were found in late October at the home of suspect Takahiro Shiraishi. (Kyodo) ==Kyodo

During his trial, Shiraishi said he would not appeal his sentence even if given the death penalty.

According to the ruling handed down on Dec. 15, Shiraishi strangled and dismembered his victims -- eight women and one man aged 15 to 26 -- from late August to late October in 2017 and sexually assaulted all the female victims. He lured his victims to his home and stole cash.

His defense lawyers had argued he was guilty only of the lesser charge of homicide with consent, saying he had his victims' tacit approval based on messages they sent him.

But the court concluded the nine victims did not consent to being killed, while also rejecting the defense's claim that Shiraishi was possibly either mentally incompetent or in a state of diminished capacity at the time of the crimes.

Photo taken from a Kyodo News helicopter on Oct. 31, 2017, shows an apartment building in Zama, Kanagawa Prefecture, where police found nine dismembered bodies in one of its units. (Kyodo) ==Kyodo

The presiding judge, who said that "the viciousness of the crimes was on a level rarely seen in Japan's history," ruled that Shiraishi's motive was "monetary gain and sexual satisfaction" and handed down the death penalty as sought by prosecutors.

Although the defense team is able to submit a revocation to court of the defendant's withdrawal of the appeal, chief defense counsel Akira Omori said they do not plan to do so.

Shiraishi is believed to have promised to help his victims die via Twitter, using his handle that loosely translates as "hangman" and inviting them to his apartment, after they had expressed suicidal thoughts.

The victims' body parts were discovered inside several coolers in his apartment in Zama, Kanagawa Prefecture, near Tokyo.