When murder by poison is depicted in fiction, it never takes more than a drop of clear liquid or a pinch of white powder in order to make the victim grip their throat, cough a bit, and fall over. Quick, clean, and quiet. The reality is not so simple. Poisoning someone to death in a way to avoid suspicion and police detection is a very complex process. The sort of poisons that can kill very rapidly at small doses tend to be staggeringly dangerous to the poisoner, not to mention exceptionally hard to come by and hazardous to manufacture.