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The first homicidal poisoner is now clearly lost in the mists of time, living as early as 70,000 BC, yet one can certainly speculate on the type of person and incident that led to the possession of this knowledge. Certainly he or she was a member of an early tribe of ancient humanity who first noticed the negative effects that exposure to certain substances had on living organisms. Perhaps it began with the observation that shortly after consuming a plant, fungus, or mineral an animal or fellow tribal member became ill and possibly died. This reasoning individual was able to conclude cause and effect by the method post hoc ergo propter hoc (after this, therefore on account of this); this method is usually considered an illogical form of reasoning but here is quite correctly applied. This observation allowed proper determination of the potential for the deleterious effects that would result from exposure to a certain substance originating from an animal, a vegetable, or a mineral source. Early man believed that flowers drew their toxicity from the vapors emanating from the entrances to the “Underworld,” that snakes developed their venom by devouring plants, and that stinging insects increased their potency by drawing venom from dead snakes. Any individual who obtained knowledge of the effects of poisons would certainly possess a great power among fellow tribal members. Perhaps the knowledge could have been used for the good of the group, as with the development of poisons for hunting, but the knowledge could certainly have been as easily used for homicidal purposes.

At the outset it might seem simple enough to define what a poison is; however, legally it is not quite as simple as it first appears. In the courts it has oftentimes been difficult to agree on the definition of “poison.” Scientific American once humorously defined a poison as “any substance in relatively small quantities that can cause death or illness in living organisms by chemical action. The qualification ‘by chemical action’ is necessary because it rules out such effects as those produced by a small quantity of lead entering the body at high velocity.”

One way to look at the motivation of a poisoner is to study how the victim is selected: some poisoners choose a specific individual, whereas others choose someone at random. The motives of these two types of poisoners are very different.

Poisoning murders can be classified into a number of groupings, depending on the motive for homicide. There can be a suicidally motivated parent who wishes to take the children with him or her. A good example of this type of killing is the case of Johanna Maria Magdalena (“Magda”) Goebbels and her husband, Joseph (Third Reich propaganda minister), who, in 1945, used cyanide to murder their six children in Hitler’s Berlin bunker, as the Allied forces approached and the end of the Third Reich was near. Another example is the case of the parents at “Jonestown,” Guyana who participated in the mass suicide there.

The analysis of whether a crime scene appears organized or disorganized can often yield valuable information about the mind-set of the killer. The poisoner usually will exhibit some characteristics of both the organized and disorganized personality. The organized poisoner has a planned offense and usually leaves no weapon or evidence at the crime scene. By contrast, the disorganized poisoner leaves the evidence in plain view at the death scene.

During an autopsy, the forensic pathologist looks for certain clues that might indicate that a poison could have been involved in the death. These clues could include irritated tissues (from caustic and corrosive compounds); characteristic odors, such as the almond-like odor of cyanide; or Aldrich-Mees lines (white bands on the nails that indicate chronic exposure to heavy metals such as arsenic) ( see Fig. 6-1 ).

The following elements are key to proving that someone has been poisoned: Discovery: This consists of legally proving that a crime was committed, and demonstrating beyond reasonable doubt that death was caused by poison, administered with malicious or evil intent to the deceased. Never forget the importance of the chain of evidence on all investigational specimens. Motive: This is critical because the investigator must clearly establish the instigating force behind the action. Why would anyone want to carry out such an act on the victim? This is where the close study of the victim (victimology) becomes central to the case. Intent: This constitutes the purpose or aim that an individual would have in commission of the act. Here the investigator will cover the desired outcome of the criminal act. Access to the poison responsible for the death: The criminal investigator must present such evidence as proof of sale of the poison, with such things as receipts or the signature on a poison register at the point of sale. Is there any original packaging, wrappers, or containers associated with the suspect? It may suffice to prove that a suspect has had access at a workplace, used toxins or poisons in his or her occupation, or had a hobby that involved the use of the poison in question. Access to the victim: Is there any proof that a suspect has knowledge of the victim’s daily habits, could have had the opportunity to overcome any of the victim’s normal defenses, and was able to administer the poison either directly or indirectly? Death caused by poison: There must be sufficient, sound evidence that would induce a reasonable person to come to this conclusion. Remember that in order to prove death by poison, the presence of the poison in the systemic circulation and/ or body organs must be proven. The presence of the poison only in the gastrointestinal (GI) tract does not prove death by poisoning. The GI tract from the mouth to the anus is much like a garden hose, hollow and open at both ends, and therefore outside the topological framework of the body. Consequently, to have met its fatal potential, the poisonous compound must have been absorbed through the walls of the gut and entered the body’s systemic circulation so that it could get to the site that caused the untoward effect. Death homicidal: This cannot be proven analytically or by autopsy but depends on the work of the criminal investigator at the crime scene, and examination of witnesses. This proof must categorically eliminate the possibility that the death resulted from an accident, intentional substance abuse, or an act of suicide.

One may commit a battery by causing injury through poisoning. Battery, of course, occurs when a person is injured in a dangerous situation intentionally created by the defendant.

In gathering information on how poisons have been used in fictional writing, I analyzed 187 texts. The types of poisons used varied slightly from those that have been used in actual cases of murder, but the primary ones did appear. In fiction, cyanide was used more often than arsenic. Table 9-1 summarizes the poisons used in fictional writings.

As Sir Arthur Conon Doyle’s Sherlock Holmes stated to his partner, Dr. Watson, “The game is afoot,” so it is with investigators and the criminal poisoner. As homicide investigators, we must always remember that unless we remain ever vigilant, we will lose the game. Unless the possibility of poisoning is considered in the first place, the critical evidence of the crime will most likely be buried with the victim, and the poisoner will walk off into the sunset, with a feeling of superior intellect and smugness.