The nerve gas attack in March got all the attention. But if it hadn’t been for an alert cleaning woman, Japan might have suffered an even worse poison gas attack early this month.
The police said the cleaning woman, who was not identified, noticed a couple of plastic bags beside a toilet in a men’s restroom in Shinjuku Station, one of the busiest subway stations in Tokyo. She picked them up and put them beside the door for disposal later.
In fact, the bags were a sophisticated chemical weapon, set to produce cyanide gas - enough to kill, in theory, 10,000 people.
The cleaning woman apparently jiggled the bags in such a way that she disrupted the automatic trigger mechanism. When they burst into flames a bit later, that evening of May 5, the fire was small enough that the police were able to put it out in time to avoid a chemical reaction that would have produced cyanide gas.
The police are investigating the case as attempted murder. But for now there is no evidence linking it to Aum Shinrikyo, the religious sect whose leaders were arrested on Tuesday on murder and other charges arising from the March 20 nerve gas attack, which killed 12 people and injured 5,500.
Still, the police are sure to be questioning those they have arrested about the cyanide incident.
The police reported the attack a day after it happened, but it was not clear then how close Tokyo came to a major disaster. It now seems that only luck averted a catastrophe.
The cyanide device was placed near a restroom vent with a fan that is piped to a subway platform, several Japanese news organizations reported. Vents in other restrooms go to the ground outside, where gas would be dispersed and hurt fewer people, so it appears that the terrorists may have had special knowledge of the station’s ventilation system.
The cyanide would have been produced if sodium cyanide, in one plastic bag, had mixed with sulfuric acid, in the other. The automatic trigger produced only a small fire that burned through just one bag by the time police arrived.
The 4.4 pounds of fresh sodium cyanide used would have produced about 2.2 pounds of cyanide gas - enough theoretically to kill 10,000 people, according to Tadashi Miyasaki, a chemistry professor at Showa University. But he added that he had no idea how many people would have been killed in actual conditions in the subway station.
Sulfuric acid is easy to obtain in Japan, but the sale of sodium cyanide is restricted and chemists said it would be quite difficult to obtain 4.4 pounds of it.
The police have recovered a stockpile of sodium cyanide from the headquarters of Aum Shinrikyo.
The police have a witness who described seeing suspicious people at the time when the cyanide device was left. One man using the restroom overheard two people in the stall where the plastic bags were left saying things like “did it leak?”
They seemed surprised upon leaving the stall to realize someone else was nearby. They carried a box, were wearing gloves and acted so strangely that the witness followed them as they left the subway station.
At that point, the witness was accosted by another man who greeted him as if he were an old friend. The man then apologized, saying he had made a mistake, but by then the two men had disappeared.
According to Japanese newspapers, which have quoted police sources in describing the witness, the authorities believe that the third man was an accomplice who realized that his friends were being followed.