Japan's top court on Friday dismissed an appeal by the defense of a former policeman who was given the death sentence for the murders of his wife and two children in 2017, exhausting his legal options.

Five judges on the Supreme Court's Third Petty Bench unanimously upheld two lower court decisions that sentenced Mitsuru Nakata, 45, to death for the murders in Ogori, Fukuoka Prefecture. His defense had argued a third party could have been responsible.

Presiding Judge Yasumasa Nagamine said Nakata's disregard for human life was "extreme, based on his determined and strong intention to kill," adding that capital punishment is "unavoidable" as he has failed to reflect upon the crime and show remorse.

According to the previous rulings, Nakata, then a sergeant with the Fukuoka prefectural police, strangled his wife Yukiko, 38, son Ryosuke, 9, and daughter Miyu, 6, at their home sometime between the late hours of June 5, 2017, and the following morning.

"It is a logical assumption that the defendant killed his wife as his resentment (against her) erupted," the Fukuoka District Court said in 2019, rejecting the argument a third party may have committed the murders.

Regarding his two children, the district court said, "It is presumed that he lost his presence of mind after the death of his wife and killed them in the heat of the moment."

In 2021, the Fukuoka High Court denied an appeal, saying the lower court's decision to impose the death penalty was correct.

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