The Supreme Court on Friday upheld the death sentence of a 42-year-old woman convicted of killing three men she met through an online dating service in the Tokyo area in 2009.

Although Kanae Kijima had pleaded not guilty, the top court ruled she killed all three men — Takao Terada, 53, Kenzo Ando, 80, and Yoshiyuki Oide, 41 — between January and August of 2009.

Based mainly on circumstantial evidence, the lower courts determined that Kijima — who has changed her surname to Doi while on death row — committed the crime and rejected defense counsel's argument that the victims could have committed suicide or died by accident. The cause of death in each case was carbon monoxide poisoning.

Kijima met each of the three men online, maintaining relationships with and receiving gifts from each before they died.

In March 2012, the Saitama District Court found her guilty of murder and handed her the death sentence as sought by the prosecution. The ruling declared that she bought coal briquettes and sleeping pills, prepared stoves and then stayed with each of the drugged victims until the moment before death.

In March 2014, the Tokyo High Court upheld the death sentence, saying she committed the crimes to maintain a luxurious lifestyle.