Kiyohide Hayakawa, the 51-year-old former "construction minister" of the Aum Shinri Kyo cult, was responsible for producing the sarin gas that killed 12 people and sickened thousands when it was released on crowded Tokyo subway trains in March 1995.
He was also found guilty of complicity in two murder cases, including the killing of a lawyer who was offering assistance to people trying to leave the cult.
"It is unforgivable that he showed no hesitation to kill in the interest of the religious group," Tokyo District Court Judge Kaoru Kanayama was quoted as saying by the Kyodo News agency. "There is no room at all for mercy. We cannot see even a fragment of humanity in him."
Hayakawa is the third Aum member to be given the death sentence since late June. Satoru Hashimoto, 33, was given the same punishment Thursday. Both men played a part in the brutal murder of anti-cult lawyer Tsutsumi Sakamoto, his wife and infant son in November 1989.
Hayakawa was also convicted of strangling of a young cult member in February 1989.
Still on trial is Shoko Asahara, the enigmatic, charismatic guru who was the force behind the Aum cult.
Like several others among the 14 cultists indicted for crimes, Hayakawa's defense rested on the claim that he was brainwashed by the nearly-blind, bearded Asahara.
In Japan, the death penalty is carried out by hanging. The names of those executed here are not announced, but word usually leaks out. Nothing has yet been heard of any Aum executions - and they may not occur for years. Last December, the Justice Ministry announced two executions, and said they were the fourth and fifth carried out in 1999.
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