Any reader of old-school mystery novels knows what the smell of bitter almonds signifies: death by cyanide, my dear Watson. And that's because some plants, including apples and bitter almonds, have cyanide in them to discourage herbivores from devouring them.
But don't fret; bitter almonds aren't the same as sweet almonds, the ones we eat in the United States. Since about 20 bitter almonds are enough to kill an adult, they aren't sold here. That said, almond extract is made with the oil of bitter almonds, but rest assured, it can't be used as a murder weapon.