When one hears the words homicidal poisoning, the first thing that comes to mind is often the sweet, misguided aunts of Mortimer Brewster and his wife Elaine Harper in the comedy "Arsenic and Old Lace."
Calling it one of their "charities," the aunts explain to Mortimer that they end the presumed suffering of lonely old bachelors by serving them elderberry wine spiked with arsenic, strychnine and "just a pinch of cyanide."
In real life, homicidal poisoning is anything but funny and usually not committed by someone people refer to as "sweet." The perpetrators carry out these sinister crimes through cunning and careful planning. Their subterfuge deceives their victims who unknowingly ingest poisons and suffer dire, and often lethal, consequences.
But how does an investigator know when a victim's death is due to premeditated poisoning as opposed to suicide or accidental ingestion? The savvy detective familiarizes himself with the signs of accidental poisoning, signs of possible toxins and the forensic tests used to prove homicidal poisoning took place.
Poisonings' fatal attraction
The terminally ill, mentally incapacitated, drug addicts, the elderly and the very young are at highest risk of poisoning. The other high-risk group is the unwanted spouse or lover. The offender is usually personally involved with the victim and is often in the role of caregiver. Poisoners often position themselves as an individual trying to "nurse" the victim back to health.
Why do they do it? Poisoners often derive pleasure from seeing their victims suffer, frequently staying to watch their target experience the poison's effects. The thrill of the poisoner's power over the victim is what motivates the perpetrator to serially offend.
There are of course other motivations for homicidal poisoning. There is a syndrome called Munchausen Syndrome by Proxy. In the actual syndrome called Munchausen Syndrome, a person may harm themselves to gain attention from family and medical personnel. In Munchausen Syndrome by Proxy, the harm is done to others, usually children. There are documented cases of mothers poisoning their children in order to attract attention and sympathy from others.
Today, perpetrators of homicidal poisonings are often employed in the medical or caregiving fields. Though there are no proven theories to explain this phenomena, perhaps their behavior is similar to that of pedophiles, who often take on roles in positions of trust over children, such as coaches, clergy and other professions, in order to gain access to their victims. Poisoners, in some cases, take on jobs that give them access to poisonous substances, and having poisons (drugs) in ready reach and extensive knowledge of their effects may be what tempts perpetrators to use them in a crime.
The authors of a 2004 FBI study on homicidal poisonings were unable to find much information on the personality traits of people who use poison to kill. They did speculate, however, that a large number of poisonings go undetected.
A poison for all tastes
There are many definitions of what is a poison. Some classifications break poisons down into the category of vegetable, mineral or synthetic. Others categorize poisons as organic or inorganic. Some simply describe poisons as any substance that can cause harm to life. Basically, this definition covers everything. However, it is the substances that can be lethal in small amounts that are most easily used in homicidal poisonings. This helps narrow the possibilities somewhat.
The ideal poison for committing a homicide must be: odorless, tasteless, difficult to detect and mimic the symptoms of naturally occurring diseases, finds Anil Aggrawal, professor of Forensic Medicine at the Maulana Azad Medical College in New Delhi, India.
From these basic definitions, there are literally thousands of substances perpetrators can choose from to commit homicidal poisoning. It is much easier to detect these substances today thanks to modern scientific methods and advances. However, unless the death is unexpected or the circumstances questionable, it is unlikely extensive testing for more exotic substances will be performed. The following is a list of some of the common toxins that have been employed in homicidal poisonings over the centuries.
Arsenic. Known as the King of Poisons and the Poison of Kings, this poison's reputation comes from its consistent use within the upper classes to poison family members. Arsenic is found in two basic forms, with both being extremely damaging to humans and other animals.
- Inorganic. This type comes in many forms. High concentrations may occur in groundwater caused by natural leaching or disruption of the earth's surface by mining activity. The two types which are most commonly found in groundwater are Trivalent and Pentavelant Arsenite. It is also found in minerals and ores. Arsenic compounds also were, until recently, used in pressure-treated wood as an anti-fungal and insecticide. Inorganic arsenic is also found in plastics.
- Organic arsenic is found in seafood and is easily metabolized in the body.
Until the late 1700s, a reliable test for arsenic's presence did not exist. By the mid 1800s it was fairly easy to spot small amounts of arsenic in human tissue. However, problems remain with the discovery of arsenic and the diagnosis of murder because the presence of arsenic in the victim's remains may not necessarily indicate foul play. Conversely, when someone dies of deliberate arsenic poisoning, it may not be distinguishable from naturally occurring exposure.
Arsenic has been used in many ways through the centuries. Arsenic Trioxide is currently used to treat acute leukemia and psoriasis. In the 18th, 19th and 20th centuries, arsenic was used to treat people with syphilis. The Union Army during the U.S. Civil War employed embalmers to preserve dead soldiers' bodies so they could be sent home. The practice proliferated and was soon popular across the Americas. Bodies were treated with numerous arsenic-based remedies ranging from a couple of ounces to more than 10 pounds of arsenic-based fluids. The use of arsenic-based embalming fluid stopped in 1910, but old cemeteries contain extremely high levels as does the groundwater around them, note John Konefes and Michael McGee on www.waterindustry.org. Modern victims of homicide buried in these areas may show high levels of arsenic, though their deaths are not attributable to poison. People drinking from sources of groundwater in the area also may be affected. Arsenic is a known cancer-causing agent, and in some areas, such as Bangladesh, the World Health Organization estimates cancer rates to be more than 200,000 in areas with arsenic-contaminated well water. Clearly the presence of arsenic does not necessarily point to a homicidal poisoning.
Cyanide. This substance seems to be a favorite in mass homicides, suicides and politically motivated killings. Cyanide gas was used by both the Nazis and the United States in gas chambers. In the Jonestown murders of more than 900 people, cyanide was placed in a sweet drink and given to the members of the Peoples Temple led by Jim Jones. Cyanide is also a favorite of spies and other politically motivated groups. Undercover agents use it to kill themselves when capture is imminent. However, it is not a favorite for the average poisoner, most likely because it kills rapidly rather than mimicking an illness.
Cyanide comes in a number of forms. The three most widely used and the most lethal are: hydrogen cyanide, sodium cyanide and potassium cyanide.
Cyanide is found in insecticides and poisons intended for rodents. It is also a by-product of the combustion of fossil fuels and is found in cigarette smoke.
A person who has been poisoned with cyanide may have the smell of bitter almond on their breath. But while approximately 60 percent of the population can detect this smell, the other 40 percent cannot. However, cyanide can be found at high concentrations in the victim's blood and urine if the samples are taken soon after exposure.
Thallium. Another toxic heavy metal which is used by poisoners, this metal is soft and pliable and has a bluish tinge to it. It was used in ant and rat poison and as a treatment for ringworm.
The telltale sign of thallium poisoning is the loss of a victim's hair. Before the discovery of the toxic effects and the symptoms of exposure, thallium was a popular poison because it was odorless and tasteless. According to the Centers for Disease Control and Prevention's (CDC's) thallium fact sheet, production of this poison halted in 1984 due to concerns about its toxic nature.
Strychnine. This is a poison that, when given in large enough doses, produces a dramatic and horrifying death. The end result of a death by strychnine is the victim's body frozen in mid-convulsion with the eyes wide open, notes the CDC strychnine fact sheet. Death occurs approximately 15 to 60 minutes after exposure, which leaves plenty of time for the perpetrator to escape.
Strychnine is a colorless crystal derived from the Strychonos nux Vomica plant found in India, Sri Lanka, Australia and the East Indies. In the past it was used to treat constipation and other stomach problems in humans. Today it is found in rat poison and street drugs, such as heroin and cocaine, notes the CDC fact sheet.
This poison hijacks control of nerve signals to the muscles. It puts the muscles into the permanently "on" mode. At low doses it causes: fearfulness; jumpiness; rigidity of the arms, legs and jaw; muscle spasm; and fever. The victim is conscious of these symptoms. At higher doses the victim experiences uncontrollable convulsion eventually leading to muscle exhaustion and the inability to breathe.
Aconitine. This is an alkaloid derived from plants of the genus Aconitum. These plants are very common and are found in gardens and in the wild in Europe and the Americas. Common monkshood is one of these plants and is found naturally growing in regions above 1,200 feet in altitude. Most people who have taken a walk in the forested areas of Alaska, northwestern Canada or the foothills along the Rockies have seen this plant growing wild. It has brilliant blue flowers and grows along the edges of lakes and marshes.
Aconitine is one of the most toxic alkaloids. Simply holding the roots for a period of time can be fatal to a child. As little as 2 mg is fatal to adults, according to the "Journal of Ethnopharmacology."
Symptoms of aconitine poisoning are cold clammy skin, salivation, nausea, rapid pulse and loss of feeling in the extremities. Aconitine also causes heart arrhythmia. All of these symptoms mimic a heart attack. Aconitine also is difficult to detect in the body due to the small amounts required to be lethal.
Atropine. This poison is an alkaloid extract to the Deadly Nightshade plant and related plants in the family Solanaceae. In very small amounts it has medical applications such as the treatment of allergic reactions, to dilate the pupils in opthamalic situations and to treat some gastric conditions. In overdose amounts, atropine causes fibrillation of the heart, nausea, blurred vision and staggering. The symptoms can be initially mistaken for alcohol intoxication.
Antimony. With both metal and non-metal forms, this poison is similar to arsenic. Occurring naturally in ores, there are many uses for antimony though it is highly toxic and known to cause cancer. Groundwater contaminated by either natural erosion or human activity is a common source of antimony.
Antimony is found in batteries, medicines, bullets, ceramics and fireproofing materials. The symptoms of antimony poisoning are similar to arsenic, and death occurs within a few days.
Poisons occur naturally in thousands of forms. If you include the synthetic products produced by chemical and pharmaceutical companies, there are millions of possible concoctions. Fortunately there are some effective modern techniques that can help an investigator narrow down the possibilities if poisoning is suspected. The most critical factor in identifying homicidal poisonings is being aware of what these cases look like. By asking the following questions, an investigator may be able to conclude a homicidal poisoning has occurred.
- Was the death sudden?
- Has the caregiver been associated with other illnesses or death?
- Did the victim receive medical treatment and appear to recover only to die later?
- Did the caregiver have access to restricted drugs or other chemicals?
- Was the victim isolated by the caregiver? Did the caregiver position himself to be the only one with access to the victim's food or medications?
- Was there a history of infidelity of either the victim or spouse?
- Is there a history of the deaths of more than one child?
While these are just some of the questions to ask, if any suspicion of homicidal poisoning exists, investigators can do a number of things. For instance, detectives who suspect the suspicious death of a child can review the child's hospital records. The offender may be associated with the death of more than one child or person under his or her care. A thorough history of the caregiver's association with ill or deceased persons is essential in revealing a pattern of behavior. Remember to check records from more than one state. If the caregiver has access to transportation, he or she may take the victim to a number of hospitals or doctors in order to avoid suspicion. Some hospitals routinely flag patients who are examined at the hospital more than three times. Once a child is flagged, the medical staff will investigate the possibility of abuse.
The sudden death of an otherwise healthy adult also is cause for suspicion. Autopsies routinely screen for some toxins, but it should be determined in advance if the caregiver or spouse had access to unusual substances. This is particularly important if the persons with access to the victim can readily obtain uncommon medicines.
Pick your poison
Once the case goes to the forensic toxicologist, the real fun begins. There are literally thousands of poisonous possibilities. It is the job of the forensic toxicologist to narrow down the list of poisons that may have been used. This is done in several stages.
- Although unlikely, if the death scene is staged to look like a suicide, there might be needles and syringes, dishes or pill bottles as well as chemical containers present. These items should be tested to see if they yield any evidence of poisonous substances.
- The victim's urine can be tested for the presence of certain drugs. This is common in athletes and employment drug testing. However, some drugs will not be present in urine while others metabolize in the body into other substances. For example, forensic scientist Richard Saferstein notes that a toxicologist searching for the presence of heroin would be on a bit of a wild goose chase, since heroin rapidly metabolizes into morphine in the body. Substances that cause instant death may not be present in urine because the victim died so rapidly, the poison never reached the bladder.
- Blood and tissue in fairly small amounts can be used to screen samples in the hopes of paring the list of possible poisons, and then used in more specific tests to confirm the type of poison present. Many poisonous substances can be defined as either acids or bases. Using the pH scale of 1 to 14, with 1 being the most acidic, various substances can be added to water to determine how they affect the pH. Water is neutral at 7 on the scale. Adding an acidic substance to the water will push the acidic reading to between 1 and 7 on the scale. The opposite happens if a basic substance is tested. The scale reading will be in between 7 and 14.
In this way the toxicologist can determine what type of drug is present. For example, Saferstein points out barbiturates and aspirin are acidic drugs. Methadone, amphetamines and cocaine are bases. Some other poisons are tested for in the same way. These poisons include industrial products, pesticides and bio-toxins. Bio-toxins are very difficult to identify and come in several forms.
Once the general nature of the substance has been determined, several other tests can be used to confirm the exact nature of the substance. The most common tests for drugs are thin-layer chromatography, mass spectrometry and immunoassay, says Saferstein.
- Check the victim's hair and nails. Some poisons such as arsenic can cause specific growth patterns in the hair and nails of the victim. This only occurs if the poisoning takes place over a period of time as opposed to a single fatal dose. Chronic poisoning also may cause toxins to build up in the victim's hair follicles. The rates at which a toxin is stored differs between light-haired and dark-haired people. Dark-haired individuals seem to have higher levels of toxins in their hair follicles.
Poisoning is a unique type of crime. It is strangely "accepted" as less of a crime than a homicide involving physical violence. But this dastardly crime takes cunning and planning and causes its victims suffering beyond comprehension. Investigators must be ever-vigilant in their efforts to detect homicidal poisoning and bring its toxic perpetrators to justice.
Kathy Steck-Flynn, a member of the Canadian Society of Forensic Scientists, teaches seminars in forensic evidence and entomology. She writes the forensic science section for "Crime Watch Canada," where she is employed as a staff writer. She can be reached at firstname.lastname@example.org.