
ANY substance that when taken in sufficient
quantities causes a harmful or deadly reaction.
(Sufficient quantities – how much enters the body, over
what period of time)
1. Intoxicant requires an ingestion of large quantities
before it is lethal
Ex: Carbon Monoxide, Alcohol, heavy metals (mercury,
lead, selenium)
2. “True” Poison – requires only a tiny amount
Ex: Cyanide
Effects of toxins do not cause VISIBLE changes in
the body in living people or during an autopsy.
 Medical Examiner will collect fluids and tissues for
testing
 Toxins are sneaky! Biotransformation can change
one chemical into another within the body due to
metabolism.
 The toxicologist may have to look for a
different sign of the toxin.

1.
2.
3.
4.
5.
6.
7.
Blood – most useful… tells what is going on at the time of
death.
Urine – Easily obtained… can’t determine whether a drug was
exerting any effect at time it was collected.
Stomach Contents
Liver
Vitreous Humor – eyeball fluid… resists decay…may be the
only fluid left in a decaying body
Hair – absorbs heavy metals and provides timeline of
ingestion
Insects – that feed on the corpse will have elevated levels of
certain drugs
Toxins will be most concentrated at the point of entry:
a. Ingested Toxins – show up more in the stomach, intestines,
and liver
b. Inhaled Toxins – show up in the lungs
c. Injected Toxins – linger in tissues around point of injection;
muscle slows down the transfer to the bloodstream.
d. Intravenously (IV) – will bypass the stomach
and liver going directly into the bloodstream
therefore quickly distributed

Cyanide – very lethal
 ME will notice a BRIGHT cherry red color to the victim’s blood.

Strychnine – plant based rat poison
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Extremely bitter taste: hard to disguise
Causes a LOT of pain: Not typical in suicides
Causes convulsions
Death is caused by asphyxia

Ethylene Glycol – antifreeze
 ME will find crystals in tubules of kidney

Heavy Metals – Arsenic, Mercury, Lead, Thallium
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All behave slightly different but cause gastrointestinal injury
Leads to nausea, vomiting, diarrhea (bloody)
Damages kidneys, liver, brain, and nerves
Arsenic poisoning often is mistaken for food poisoning
Mercury poisoning causes brain damage and birth defects

Succinyl Choline – injectable drug
 paralyzes all the muscles of the body
 Leaves behind little evidence of presence

Corrosive Chemicals – Strong alkalis bases (lye) and acids
 When ingested…corrode and burn tissues of digestive track
 Causes bleeding, shock, and death
 Rarely used in homicides…mostly accidental children ingestion.

Carbon Monoxide – metabolic poison
 Prevents oxygen from binding to hemoglobin in red blood cells
 “Silent Killer” – causes suffocation
Blood Alcohol concentration
• BAC is the amount of alcohol in the
bloodstream measured in percentages
– BAC = 0.10%
 means a person has 1 part alcohol per 1,000 parts
of blood in the body
• The ratio of alcohol in blood to alcohol in alveoli
air is 2100 to 1
(1 mL of blood will contain about the same
amount of alcohol as 2100 mL of breath)
 Portable, roadside breath tester.
▪ Breath Testing - direct relationship between BAC and amount of alcohol vapor
in breath.
 Walk and turn and/or one leg stand (divided attention
test).
 Horizontal gaze nystagmus- involuntary jerking of eye
as it moves to the side - more intoxicated the less the
eye moves before jerking.