A serial killer dubbed the "black widow" was handed a death sentence Tuesday over the murders of her husband and two common-law partners, as well as the attempted murder of an acquaintance, between 2007 and 2013.

The ruling by the Kyoto District Court came despite a not guilty plea by the defense counsel of Chisako Kakehi, 70, citing a lack of physical evidence. The defense had also argued that Kakehi could not be held responsible as she had developed symptoms of early-onset dementia at the time of the murders.

"It was a heinous crime driven by greed for money. The death sentence cannot be avoided even after fully taking into account dementia and other factors," presiding Judge Ayako Nakagawa said in the ruling.