Q: I have a character who needs to die after licking an envelope. I would prefer a fairly quick demise. What sort of poison could the murderer use? It would need to be something that doesn’t taste too awful or she’ll stop licking it!
A: There are very few poisons that work instantly in small doses, but cyanide would fit your needs and can be acquired fairly easily.
Cyanide is quick and even if someone attempted to save the victim, it is next to impossible because treatment with a Cyanide Antidote Kit or a Cyanokit must begin immediately if any chance of survival is to be realized and people don’t usually carry these kits around. Simple CPR won’t do it. This is because cyanide is a “metabolic poison.” It basically shuts down the ability of cells to use oxygen. The red blood cells cannot carry oxygen to the tissues and the tissue cells of the body can’t use the oxygen anyway. It is as if all the oxygen were removed from the body instantly. This process is immediate and profound and leads to death in 1 to 20 minutes, depending on the dosage and a few other things. Even of CPR were begun immediately, it would be ineffective since the cells couldn’t use the oxygen supplied by this process.
Symptoms would begin very quickly in the delivery method you have chosen since the cyanide would absorb rapidly through the membranes of the mouth. The symptoms are rapid breathing, shortness of breath, dizziness, flushing, nausea, vomiting, and loss of consciousness. Maybe seizure activity. Then death. This could happen in a matter of minutes. Your victim might develop sudden, severe shortness of breath, a flushed face, perhaps clutch at his chest, collapse to the floor, and die, with or without having a seizure in the process. This would look very much like a heart attack. His skin might appear pinkish and if he hit his head or scraped an elbow in his fall and bled, the blood is a noticeably bright cherry red due to a chemical reaction between the cyanide and the hemoglobin molecules in the red blood cells.
Potassium Cyanide (KCN) and Sodium Cyanide (NaCN) are your best bets. They are white powders with a faint bitter almond smell, which most people do not notice. Both dissolve readily in water and saline. One caveat. Your killer must be careful in handling the KCN or NaCN as both readily absorb through the skin and could do in your killer. Rubber gloves or a complete avoidance of direct contact with the powder would be wise.
KCN and NaCN are used commercially in metal recovery such as extracting gold or silver from their ores and in electroplating such metals as gold, silver, copper, and platinum. They could be pilfered from a jewelry or metal plating company or could be purchased from a chemical supply firm.
In your story, the powder could be dissolved in water, applied to the envelope glue, and allowed to dry. When your victim licked the glue, he would develop the above symptoms within a very few minutes and would then collapse and die. This could take as little as two or three minutes.