Saturday, November 10, 2007

The Myth of the Untraceable Poison

Doug P. Lyle, MD (Guest blogger)

One of the most common questions I get from writers is: Is there a poison that can’t be found in a corpse? The answer is No. And Yes.

Much depends on the state of the corpse when it is found. If severely decayed or completely skeletonized, the medical examiner and the forensic toxicologist have their hands tied. Mostly. There are some toxins, such as the heavy metals (mercury, lead, and arsenic are common ones), that can be found in bones and hair. But most toxins can’t be found in corpses that are severely decayed or simply bones.

In a more or less intact body, your villain can still get away with the murder by poison. That is, until your clever sleuth figures out that something is amiss and solves the crime.

The first thing your murderer must consider is how to make the poisoning look like something else. An example would be an elderly person with heart and lung disease who dies in his sleep. In this case, the person's private physician would sign the death certificate as a natural cardiac death and almost always the M.E. will accept it. Why? Because there is an old adage in medicine that says: Common things occur commonly. Most people who die in this situation do indeed die from natural causes, so searching for something more sinister would be neither logical nor practical. If the M.E. accepted the private physician’s cause of death, no autopsy would be done and no toxicological examinations would be undertaken. An overdose of morphine or digitalis or arsenic or anything else would go undetected.

Unless someone asked questions. Maybe a high-dollar inheritance or insurance policy is in play. If an inheritance, one family member could suspect another and ask questions. In the case of a large insurance policy, the insurance company would look under every stone before paying off the policy. Or your sleuth could have some reason to suspect that things are not as they seem. In any of these situations, the ME might be moved to open a file and investigate.

But if your killer is clever, he might be able to keep the M.E. completely out of the picture or at least give him an easy answer for the cause of death. If no murder is suspected, he'll take the path of least resistance, which is also the cheapest route. Remember, he must live with and justify his budget annually. If he is wasteful he'll be looking for a job. So, give him a cheap and easy out. Your sleuth will then have to battle the M.E. to get the case re-opened.

The second thing a clever poisoner can do is to use a poison that is not readily detectable and will slip through most drug screens. Toxicology testing follows a two-tiered approach. Screening tests, which are easier, faster, and cheaper, are used to identify common classes of drugs such as narcotics or amphetamines. This only tells the M.E. and toxicologist that some type of narcotic or amphetamine is present, but not which one. Determining which one requires more sophisticated, time-consuming, and expensive confirmatory testing. And if the screening tests are normal, no further testing is warranted and the M.E. would not spend the time and money to go further down that road.

Drug screens typically test for alcohol, narcotics, sedatives, marijuana, cocaine, amphetamines, and aspirin. Some screen for a few other classes. Once a member of a class is identified, then confirmatory testing will determine exactly which member of the class is present and in what amount. For example, if narcotic is found in the screen, further testing might show that the actual narcotic present is morphine. Or an amphetamine might be further analyzed and this might show that methamphetamine is the culprit.

Your poisoner could use a poison that would not be found in the typical screen. Things such as arsenic, selenium, and most plants (oleander, deadly nightshade, etc.) do not show up on the typical tox screen and when the screen came back negative, the M.E. might not go further. Why would he spend the time and money without a good reason? This is where your sleuth steps in to shake things up. But if a poison is suspected and if the funds and interest to pursue it are present, anything can be found in an intact corpse. Using gas chromatography in conjunction with either mass spectrometry (GS/MS) or infrared spectroscopy (GC/IR) will give a chemical fingerprint for any molecule. And since each molecule has its own structure and thus its own fingerprint, every compound can be distinguished from every other one.

To write a good mystery that will keep the reader guessing to the end, you must plot the nearly perfect murder. This way when your sleuth cracks the case, he or she will be a true hero. If poisoning is your killer’s chosen weapon, then use the above principles to make your plot as clever and convoluted as possible. Have your killer mask the death as natural or use some poison that is not readily detectable in screening tests and then your sleuth must be very clever to solve the case.

There are several sources for you to search out poisons and to discover how they act and how they are identified. Google, of course, and try plugging into your state poison control center. My books, Forensic for Dummies, Murder and Mayhem, and Forensics and Fiction cover a number of poisons. I also recommend Howdunnit: Book of Poisons by Serita Stevens and Anne Bannon from Writers’ Digest Books. It is a great resource for poisons of all types.

Visit the Writers Medical and Forensic Lab at


A Paperback Writer said...

So, even the venom part of "The Adventure of the Speckled Band" wouldn't work, then, would it? Doyle never was big on research, and that snake story has always bugged me (rewarding the snake with milk -- of all things- whistling to the snake). Granted, it's not a modern story, but still.....

Anonymous said...

Doug P. Lyle, MD (Guest blogger----------
youre dead wrong. 'md'. like that means anything. you know nothing. thats not a 'myth'. there is untraceable poison. but the TRUTH is Jesus Christ. all that you talk about your science and medicine bullshit is all garbage. Jesus Christ IS the TRUTH. Jesus Christ IS THE LIGHT. Jesus Christ IS Almighty God manifest in the flesh, and He saves by His grace.Jesus Christ IS THE LIGHT. Jesus Christ IS Almighty God manifest in the flesh, and He saves by His grace.

youre a villain. Im like hero by Gods grace. Jesus Christ IS Almighty God manifest in the flesh, and He saves by His grace.

youre dead wrong. death wont get you sober. death gets you dead moron. Jesus Christ IS the One who saves. Jesus Christ IS Almighty God manifest in the flesh, and He saves by His grace. Jesus Christ GIVES us eternal life FREELY by His grace. Jesus Christ ABOLISHED death, by dying on the cross for our sins, and RISING again for our justification by His grace. Jesus Christ defeated the devils power, and Jesus Christ destroyed the devil, by Jesus Christ dying on the cross four our sins, and by Jesus Christ RISING FROM THE DEAD. Jesus Christ SAVES by His grace.

your white venoms and deaths are nothing. they wont do anything for you. Life more abundantly, ETERNAL life is in Jesus Christ by His grace. Jesus Christ gives sobriety, and Jesus Christ heals and delivers and saves us by His grace. understand that Jesus Christ IS the Only One who can do the things that we desire for us, by His grace. Jesus Christ saves.

Anonymous said...

wait, what? hahahaha. so because Jesus Christ supposedly existed, there must be untraceable poisons?

stupid fundies...

Anonymous said...

wtf was that about, he got off topic

Anonymous said...

yeah he/she is a fucking moron jesus fucking god blowing cunt rag for saying all that shit about how the truth is jesus christ. im betting that person who posted that was that fucking lady from that trading spouses show that went psycho on everyone because a few kids and a dad were not god fearing.

people like that make me sick. trying to empose that they are right because they got some faith in a belief.

granted poisoning is difficult to hide from a toxology center (besides destroyer mushrooms and certian types of powerful halluciangens hehehe....) doesn't give that self rightous fuck to go off on that person because of his chosen field of expertise.

people that have the nerve to say things like they know nothing cause of some fuck who may or maynot existed (i think the bible is a crock of shit, just good stories to entertain the masses for a few thousand years so that priests and rabbis can rape and molest small children after a drunken night of being in the confession box drinking the blood of christ.)

I have no problem with peoples religions. i have a problem with people using religion to being geniune dick faces and try and forciably sell there idea to the masses.

honestly people that think this way deserve to be put either to death or a communist country, so they can see what it feels like to have other peoples believes put over there heads.

who ever this person is, go burn in hell with the rest of your backwards christians. (no offense to the people that are christian that aren't nazi like douche bags like that jerk off!) if i saw you in the streets i would love to kick your ass straight to god himself.

and on a lighter note, Doug P. Lyle, MD, very imformative artical. enjoyed it throughly. many things i already knew but all in all very interesting.

Anonymous said...

Great article! Thanks Doug P. Lyle, MD. Very informative. I am currently enjoying your forensics for dummies book and finding it extremely helpful.

As for the random fundie blog troll commenter, you made me laugh so I guess your little outburst was worth it after all. Your exuberant love of incorrectly placed capital letters entertains me. :P

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Just sayin

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