The Tokyo High Court upheld the death sentence on a former senior Aum Shinrikyo cultist Thursday for his involvement in two separate murder cases and in building a plant to mass-produce nerve gas.

Presiding Judge Atsushi Semba affirmed the Tokyo District Court's sentence, handed down in 2000, on Satoru Hashimoto, 36, finding him guilty of killing Yokohama lawyer Tsutsumi Sakamoto, 33, his wife, Satoko, 29, and their 1-year-old son, Tatsuhiko, in November 1989.

"His acts were extremely cruel and inhumane," Semba said. "There is no choice of sentencing him to life imprisonment."

Sakamoto was the leader of a group of lawyers helping families whose relatives had joined the cult.

The court also affirmed Hashimoto deserves the death penalty for his part in a sarin nerve gas attack in Matsumoto, Nagano Prefecture, in 1994, and for helping to build a sarin plant in Kamikuishiki, Yamanashi Prefecture, between 1993 and 1994.

The nerve gas attack killed seven people and injured many others.

Defense lawyers argued that the death sentence is too severe, saying Hashimoto's mind was controlled by Aum founder Shoko Asahara, whose real name is Chizuo Matsumoto. Hashimoto had no intention to commit the crimes, they said.

The lawyers said they plan to appeal to the Supreme Court.

In connection with crimes involving the cult, which renamed itself Aleph in 2001, a total of nine people have appealed after receiving death sentences in their first trials. A high court upheld the death sentence on two people other than Hashimoto.