As police and dozens of reporters looked on, a right-wing extremist on Sunday ambushed and fatally stabbed the top scientist in the doomsday cult suspected in the lethal nerve gas attack on Tokyo's subways.

The stabbing was the latest chapter in a wave of violence that has deeply shaken the Japanese, who have long taken the safety of their streets as a matter of national pride.The vigilante-style attack occurred as Hideo Murai, 36, head of the Aum Shinri Kyo (Supreme Truth) cult's "Science and Technology Ministry," was returning to the cult's Tokyo headquarters Sunday night. Murai was one of the five top leaders of the cult.

Murai underwent surgery, but died of blood loss and internal injuries several hours later. He was pronounced dead early Monday morning, police said. Television networks broke into regular programming to broadcast the attack nationwide, some repeatedly showing a knife plunging into Murai's side in slow motion.

Aum believers were shown crying hysterically as Murai was taken away semiconscious. Dozens gathered at the hospital to donate blood for transfusions.

"Why didn't the police protect him?" Yoshinobu Aoyama, the cult's lawyer, demanded after the attack. "They could have predicted this kind of thing."

Murai, 36, was believed to be a focus of the investigation into whether the cult was involved in the March 20 subway attack, which killed 12 people and sickened 5,500.

An attacker who called himself a right-wing extremist got to him first, however, pushing his way through a throng of media people staking out the cult's Tokyo headquarters and slashing repeatedly at Murai with a kitchen knife.

After Murai collapsed into the door of the Aum office in a pool of blood, the attacker dropped his bloodstained weapon and was arrested by police at the scene.

Police identified him as Hiroyuki Jo, 29, and said he claimed to be a member of a rightist organization.

Japan's state-run television network, NHK, said Jo told police he wanted to punish Murai because of trouble caused by the cult.

The cult has denied any connection with the Tokyo attack.

Yet the cult has been the focus of an intense police investigation since the March 20 subway killings. Police have conducted daily searches of cult compounds over the past month and discovered tons of chemicals and equipment that could have been used to produce sarin, the kind of nerve gas used in the subway attack.