Arsenic is an extremely toxic, metallic grey element, number 33 on the periodic table. It is one of a dozen toxic elements like lead and cadmium that are present in common items. Arsenic was once used in rat poison and is an ingredient in pesticides and herbicides.

Arsenic was once so readily available and common as a method of murder that it was called "inheritance powder."

In the Middle Ages, the toxic element was often chosen as a means of assassination, as the symptoms closely resembled death by cholera, but its use continues to this day.

In San Diego, 2007, a woman was convicted of murder for the arsenic poisoning of her husband. Her motive was to claim his army benefits.

The symptoms of poisoning from arsenic include fatigue, sensory disturbances, fatigue, muscle paralyses, blindness, convulsions , kidney damage, shock and coma. Autopsies of arsenic victims reveal signs of internal hemorrhaging.