10 Most Shocking Unsolved Crimes

In September 1982, a man named Adam Janus began experiencing chest pains, so he popped a few Tylenol. That was one of the last things he would ever do, since he dropped dead an hour later. Those tablets, it turned out, were laced with cyanide.

Six more people died from taking the poisoned pills before the authorities connected the dots and realised what these cases had in common. A nationwide recall of all Tylenol products followed.

New York City resident James William Lewis emerged as a prime suspect behind the poisonings when it transpired that he took credit for the killings in an attempt to defraud $1 billion from Johnson & Johnson, but he was only ever charged with extortion, and has since admitted that's the only thing he's guilty of.

Technically speaking, the investigation is ongoing, but the most recent development came in 2011 when Johnson & Johnson whistleblower Scott Bartz claimed the medication was tampered with somewhere along the repackaging and distribution links in Tylenol’s supply chain, rather than at retail level as previously suspected.

As a result of the Chicago poisonings, tamper-proof seals became the norm for over-the-counter medications sold in bottles.