Since the Tribune first reported on Monday about Urooj Khan's death from cyanide poisoning, the story has gripped readers. On Thursday, it was the most viewed story on Chicago Breaking News. Friday, reporter Annie Sweeney and I wanted to take a step back from the ongoing investigation and help explain to readers what, exactly, cyanide is, where it occurs and how it can be lethal.
The pathologists and toxicologists we talked to explained that cyanide, formed by the very common elements carbon and nitrogen, exists in many places you might not expect. It can be found in certain plants, seeds and soils, though usually in trace amounts. Some bacteria and fungi also produce cyanide.
When it is in a pure powder or gas form, however, it can be particularly poisonous to humans. Only about 200 milligrams is needed to be deadly.
Once inside the body, the molecule essentially prevents cells from using oxygen. Without oxygen, cells and tissues are killed and eventually a person will lose consciousness and also die.
It may take only a handful of minutes.
Though homicidal poisoning is rare, cyanide has been used throughout human history to devastating effect. It was used in the World War II Nazi death camps, during the Jonestown massacre and in the 1982 Chicago Tylenol murders.
We'll keep looking forward, too. In the coming weeks, local authorities will try to piece together yet another murder mystery involving cyanide as they continue their investigation into Urooj Khan's death.
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