Early on the morning of September 29, 1982, 12-year-old Chicago girl Mary Kellerman woke up with a sore throat and runny nose.
Her parents gave her a Tylenol capsule to take before going to school. She then collapsed on the bathroom floor.
Mary was rushed to hospital, but died within a few hours.
That same day, 27-year-old postal worker Adam Janus took the day off work because he wasn't feeling well.
He took a couple of Tylenol and then collapsed. He could not be revived.
Later that afternoon, Adam’s family went to his house to discuss funeral arrangements, when his younger brother, 25-year-old Stanley, asked for some Tylenol to ease his back pain.
His wife, 19-year-old Theresa, gave him two capsules, then took two herself. He collapsed, and then she collapsed.
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While investigators were racking their brains over the deaths, three more women passed away.
There was 27-year-old Mary Reiner who started to feel unwell on her way home from giving birth to her fourth child.
She took two Tylenol but her condition worsened and she returned to the hospital. Mary died before doctors had gotten to see what was wrong.
There was 31-year-old Mary McFarland who was at work when she got a headache. She was rushed to the hospital where she died of unknown causes.
Investigators later found Tylenol in her handbag.
And lastly, 35-year-old flight attendant Paula Prince, who stopped by the pharmacy on the way home for some Tylenol.
When her sister couldn't reach her, she went around to her apartment. She found Paula dead on the bathroom floor.
After Adam Janus passed away, an investigator, Nick Pishos, grabbed both his Tylenol bottle and the one Mary Kellerman had used.
His boss, deputy medical examiner Edmund Donoghue, told him over the phone to open both bottles and sniff them. Pishos reported a strong smell of almonds.
Both he and his boss knew what that meant: cyanide.
"I was very lucky because this investigator was able to smell cyanide," Donoghue remembers.
"Only about half the population can smell it."
The lab results showed the victims had enough cyanide in their blood to kill someone 100 or even 1000 times.
A press conference was held soon after, warning people not to take Tylenol. Chicago police began walking through the streets to spread the message.
"The deaths set off a nationwide panic, as stores rushed to remove Tylenol from their shelves and worried consumers overwhelmed hospitals and poison control hotlines," Time recalls.
"Chicago police went through the streets with loudspeakers, warning residents of the dangers of taking Tylenol. Johnson & Johnson, the drug's manufacturer, spent millions of dollars recalling the pills from stores."
Johnson & Johnson were able to work out that the contamination had occurred after the Tylenol had left the factory.
Police decided that someone must have taken the bottles off store shelves, opened the capsules, laced them with cyanide, put the capsules back in the bottles and put the bottles back on store shelves.
At that point, Tylenol was sold in bottles with a simple cap on top.
The tampering inspired copycats around the nation, with more than 270 incidents being reported in the following month.
Rat poison and hydrochloric acid were added to pills. Sodium hydroxide was found in a carton of chocolate milk, and razor blades in frankfurters.
Pins and a sewing needle were discovered inside chocolate bars. That Halloween, trick-or-treating was banned in some communities.
As for Johnson & Johnson, after recalling all 31 million bottles of Tylenol on sale nationwide, they decided to make some big changes.
They brought in tamper-resistant packaging, including foil seals, which soon became standard for over-the-counter painkillers. They also introduced the caplet, which is harder to tamper with than a capsule.
"As a direct consequence of the Tylenol murders, Congress approved in May 1983 a new 'Tylenol Bill' that made the malicious tampering of consumer products a federal offence. In 1989, the FDA set national requirements for all over-the-counter products to be tamper-resistant," Crime Library recounts.
"[Author and crisis-management expert] Steven Fink summed up the feeling of the nation when he stated that, 'whatever innocence we still had in the summer of 1982 was quickly shattered by the fall.'"
A week after the seven deaths, Johnson & Johnson received a handwritten note demanding that $1 million be deposited in a specified bank account "if you want to stop the killing".
It was discovered that the note had been written by a man called James Lewis.
"As you can see, it is easy to place cyanide into capsules sitting on store shelves," Lewis wrote.
"Another beauty is that cyanide operates quickly. It takes so very little and there will be no time to take countermeasures."
Lewis was convicted of trying to extort money from Johnson & Johnson and spent 13 years in jail. But he was not charged over the deaths.
He was released in 1995.
Over the years, investigators continued to scrutinise Lewis in connection with the Tylenol murders.
In 2009, FBI agents search his house, seizing his computer and other belongings after local authorities renewed the investigation.
He later attracted more attention when he self-published a novel titled, Poison: The Doctor's Dilemma.
In July 2023, Lewis was found unresponsive in his home, aged 76. His death was not ruled as suspicious.
Former Assistant US Attorney Jeremy Margolis, who successfully prosecuted Lewis' extortion case, regrets he was never brought to justice for the seven deaths.
"I was saddened to learn of James Lewis’ death," Margolis said in a statement to the Chicago Tribune.
"Not because he’s dead, but because he didn’t die in prison."
To this day, the person responsible for the Tylenol murders has never been caught.
Feature image: Today/Chicago Tribune.