The Kyoto District Court issued the ruling for 70-year-old Chisako Kakehi on November 7th. The crimes took place between 2007 and 2013.
The defense team pleaded not guilty and filed an appeal to a higher court. They say there is no evidence to prove how Kakehi obtained the cyanide. The team also argued that she could not be held criminally responsible because she has dementia.
The presiding judge said Kakehi told the court that she obtained the cyanide when she was running a printing factory.
The judge said Kakehi was with the victims when they were poisoned and began the process for inheriting their assets immediately after they died.
She also said a psychiatric evaluation shows that Kakehi did not have dementia at the time of the poisonings, and her consistent actions show that she should be held criminally responsible.
Several men linked to Kakehi found dead
Kakehi told reporters before her arrest that she did not kill her husband, and that the allegation was shocking. She said she wondered why she was being accused.
Kakehi raised suspicion after her husband, Isao, died in December 2013. Cyanide exceeding the lethal dose was detected in his body. Police began investigating his death as a possible killing.
The police later found Isao died only a month after the couple got married, and that Kakehi had taken out a large life insurance policy on him. They discovered traces of cyanide at her home.
The police also learned several other men with links to Kakehi had also died.
Prosecutors later indicted Kakehi for allegedly killing 3 people -- Isao and 2 of her former partners -- and attempting to kill and rob an acquaintance. Kakehi met the victims through matchmaking services.
Police sent prosecutors additional papers connecting her to the killings of 4 other men, but the prosecutors decided against indicting her on those charges due to a lack of evidence.
Issues in the trial
A major issue in Kakehi's trial was how to handle circumstantial evidence. The trial started in June.
There was little direct evidence to back up the charges against her. Cyanide was not found in 2 of the 4 victims. Prosecutors had a total of more than 50 witnesses testify in court.
The prosecutors said testimonies by emergency services personnel sent to the victims back up their belief that all 4 were poisoned. They also said they were sure that Kakehi poisoned the victims, as all of them collapsed when they were with her or just after they met her.
The prosecutors argued the defendant killed the men to inherit their assets or avoid paying back debts.
Kakehi's defense team said it cannot be stated that she was the only one who was able to carry out the crimes, because there was no evidence that she was with the victims before they collapsed. The team added that there was no proof that the defendant obtained and kept cyanide, and that victims may have died from illness or committed suicide.
Another major sticking point was whether Kakehi could be held criminally responsible.
A psychiatric assessment conducted by the court in 2016 shows the defendant did not have dementia at the time of the incidents. A doctor in charge testified that she developed Alzheimer's disease about 2 years ago after the incidents, but that her condition was mild and would not hinder her ability to take responsibility or file lawsuits.
Meanwhile, Kakehi changed her testimonies several times.
In July, she appeared in court wearing hearing aids. Asked by prosecutors whether she killed her husband, she replied "Yes, I thought I could pay back my debts using money inherited after his death."
But in the next court session, when her lawyer asked whether she remembered what she was asked during the last session, she said she did not remember well due to dementia.
In September, the prosecutors asked her to confirm that she had told investigators that she poisoned one of her former partners to death. She replied that she does not fabricate stories, and said she tricked him into taking a cyanide capsule by saying it was a health supplement.
But during questioning from defense shortly after that, she said she could not imagine killing him and that doing so would not have benefitted her.
The prosecutors said Kakehi understood her position and her defense team's role in the trial and had the mental capacity to take action based on her thoughts. They said that at the time of the incidents, she did not have dementia or any other mental illness, and had the ability to successfully carry out well-planned crimes.
The defense responded that Kakehi could not understand what it meant to protect herself in a trial, as her dementia had progressed since the psychiatric evaluation. They said she was already suffering from dementia back then and could not be held criminally responsible.
Expert calls the ruling "cautious"
Professor Osamu Watanabe of Konan Law School says he believes the court ruling was based on cautious examination. He says the prosecutors backed up testimonies mainly using objective evidence, including the fact that cyanide -- a chemical hard for ordinary people to obtain -- was found around the defendant.
Watanabe says now that the defense has appealed, it could take several years before a final decision. He says her trial could be canceled if her dementia gets worse.
He says this must be avoided for the sake of the defendant who has been maintaining her innocence, as well as the victims' families and society, who want to know the truth.