Tokyo -- Japan's top court Thursday rejected an appeal from a former officer of the Aum Supreme Truth doomsday cult, giving the green light for the first execution of a member of the sect that attacked the Tokyo subway with nerve gas in 1995.
The Supreme Court confirmed the death sentence on Kazuaki Okazaki, 44, who was convicted of killing four people before the subway attacks including an anti-sect lawyer and the attorney's wife and baby son.
Okazaki has no other means to appeal unless a court agrees to rehear the case if new evidence emerges. He is one of 13 former Aum members who has been sentenced to death.
Defense lawyers had argued for leniency, saying Okazaki was under "mind control" by the sect's top guru Shoko Asahara, who has also been sentenced to death.
In prison, Okazaki was adopted by a mainstream Buddhist monk and has repeatedly apologized for his crimes. As part of his conversion, he has become an avid painter of classical Zen themes.
But Judge Niro Shimada ruled: "There is no room for leniency as the sole purpose of the crimes were to defend the organization."
"Even though he surrendered to police, his criminal responsibility is extremely serious," Shimada said.
Okazaki was a founding member of the cult launched by Asahara, a bearded and partially blind former acupuncturist who preached a blend of Buddhist and Hindu dogma with apocalyptic visions.
Okazaki, whose trial started in 1996, said he and five other Aum members on Asahara's orders broke into the Yokohama home of a lawyer campaigning against the sect, Tsutsumi Sakamoto, then 33, and strangled him to death.
They also suffocated his wife Satoko, 29, and smothered to death his one-year-old son Tatsuhiko with a blanket in the November 1989 break-in.
Okazaki was also found guilty in the February 1989 murder of Shuji Taguchi, 21, who had tried to leave the cult after witnessing an earlier Aum killing.
Asahara was sentenced to death in February last year for crimes including the subway attack, in which cult members spread Nazi-invented sarin gas on rush-hour trains killing 12 people and injuring thousands more.
Asahara faces an appeal trial but not even the first hearing's date has been set as his lawyers cannot communicate with him. His daughters have said their father is ailing and mumbles nonsense.
Executions are carried out by hanging in Japan, the only major industrialised country other than the United States to practice capital punishment.
In a system criticized by rights groups, Japan gives no prior indication of when executions will take place, with inmates often waiting more than a decade on death row only to find out they will be executed hours in advance.