Here's what I've come across about untraceable poisons. I'm not sure
if any poison is "untraceable" per say, but there some which may have
no test for them yet, or as you say break down so quickly before the
person dies as to be at undetectable levels at the time of death. In
fact, an "Unsolved Mysteries" episode last week in re-runs described
an arsenic murder in which such little arsenic was used, various foods
were tested in the fridge and cabinet after suspect, but arsenic was
never actually found in detectable levels in the dead body itself.
Apparently there was a conspiracy to assassinate Fidel Castro using
one such poison, botulinum toxin.
From Operation Mongoose (link below):
"Inject an untraceable poison, botulinum toxin, into selections of
Castro's favorite brand of cigars and present the poisoned cigars to
The Atlanta Journal-Constitution has an article on an easily made
biotoxin ricin, which is made from the castor bean plant (the same
plant which we get castor oil from). This poison is purportedly being
made by Iraq and other terrorist nations and is supposedly
Atlanta Journal-Constitution article (link below):
"...an untraceable poison that is twice as deadly as cobra venom..."
One last anecdote takes me back to high school Chemistry class where I
learned that heavy water, or water with an extra neutron can be
imbibed with not much of a noticeable difference, except over time,
when the radiation starts to inhibit cell division, and certain body
processes start to fail. This is a poison which, "which would take
about 50 kg of heavy water at $300 a kg" has to be delivered in the
long run, and only a truly sadistic person would do this to somebody
else. Of course, the poison's untraceable, but the radiation would be,
but radiation tests are not done on homicide victims usually. So this
is what our class came up with as the perfect untraceable poison,
because all chemical tests on the water would come up with "water".
AJC article, "Tracking the Terrorists":
Heavy water discussion:
"untraceable poison" on google:
ricin on google:
"poison breaks down" on google:
"heavy water" radiation toxicity on google:
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