Paraquat murders

Between April and December 1985, a series of indiscriminate poisonings occurred in western and central Japan, including Tokyo, in which beverages were laced with the herbicide paraquat dichloride (and in one case diquat) and left in or around public vending machines. Victims who consumed the tainted drinks — most commonly the energy drinks Oronamin C and Real Gold, though some Coca-Cola bottles were also affected — became seriously ill or died. The first known victim drank a bottle of Oronamin C left atop a vending machine in Fukuyama, Hiroshima Prefecture, on April 30, 1985; he fell ill and died a month later.

At the time, paraquat was a widely available, unregulated chemical in Japan that could be purchased without a prescription, provided the buyer claimed an agricultural need. The perpetrator appears to have exploited a contemporaneous "buy one, get one free" promotion by Oronamin C's manufacturer, Otsuka Pharmaceutical, placing poisoned bottles near vending machines so that customers would mistake them for free promotional drinks. Additional poisonings followed in the ensuing months, including the deaths of a 44-year-old executive who drank tainted vitamin drinks on September 5 and a 52-year-old man who drank a bottle of Oronamin C in Tokyo on September 11.

By December 8, 1985, official reporting attributed at least ten deaths and 35 serious illnesses to the poisonings, though CBC News reported in 2012 that the death toll may have been as high as twelve, a figure that would make the case possibly the deadliest instance of product tampering on record. Some deaths were later theorized to be the result of copycat acts or imitation suicides rather than the original perpetrator.

Investigators concluded the poisonings were likely the work of a single person, but found no consistent victim profile, no security camera footage of a suspect, no physical evidence, and no discernible motive; the two manufacturers whose products were most affected, Otsuka Pharmaceutical and Coca-Cola Japan, reported receiving no threats or extortion demands. In response, Japanese authorities and industry groups launched a nationwide public-awareness campaign, distributing warning leaflets, posting stickers on many of Japan's roughly 5.2 million vending machines, and advising consumers to discard unclaimed free drinks and inspect bottle seals for tampering.

The case was never solved. Because Japan abolished the statute of limitations for murder in 2010, a perpetrator could still theoretically face prosecution if identified, but no arrest has been made. In the years following, regulatory changes reduced the toxicity of commercially available paraquat and diquat, though paraquat poisoning continued to account for a large share of pesticide-related deaths in Japan into the 2000s. A suspected copycat incident involving tainted school milk occurred in Mie Prefecture in December 1985, and further vending-machine and convenience-store poisoning incidents were reported in 1998 and 2019.