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Question and Answer: Can Carbon Monoxide Cartridges be Used as a Method of Murder?

13 Mar

Q: My victim is in a locked room with one small window in an abandoned warehouse and is being slowly killed by carbon monoxide fumes from little cartridges that are timed to activate at certain intervals. There is also a booby trapped bomb in a briefcase in the same room, which will be detonated when the levels of carbon monoxide are high enough. How long would it take the victim to fall unconscious? Is it possible to ignite a bombs fuse with this gas? If it is possible, and the victim is rescued before the bomb detonates would they be able to recover completely from carbon monoxide poisoning and how long does recovery take?

A: First of all, carbon monoxide will not explode nor does it readily burn so using it as a fuse or as an explosive material isn’t a possibility. You could have a carbon monoxide detector on the bomb that would ignite when a certain level was reached so in this regard it could be viewed as a fuse of sorts.

Carbon Monoxide (CO) is stealthy, treacherous, and deadly. It’s also common. You’ve seen it in the papers or on the news. A family is found dead and the cause is a faulty heater or fireplace. A suicide victim is found in his garage with the car engine running. Campers are found dead in a tent, a kerosene lantern burning in one corner. Each of these is due to carbon monoxide.

CO is a tasteless, odorless, colorless gas that is completely undetectable by humans. It results from the incomplete combustion of carbon-containing fuels—paper, wood, gasoline, and many other combustible products. Faulty stoves, heaters, and fireplaces as well as the exhaust from a car engine can fill the air with CO. Carbon monoxide poisoning is a more common cause of death in fires than is the fire itself. In your scenario, you supply the CO via cartridges so none of this is needed in your story, but this may be part of the investigation as to why the victim had CO toxicity—-if the cartridges aren’t found, etc.

Carbon Monoxide’s treachery lies in its great affinity for hemoglobin, the oxygen (O2) carrying molecule within our red blood cells (RBCs). When inhaled, CO binds to hemoglobin producing carboxyhemoglobin. It does so 300 times more readily than does oxygen and thus displaces oxygen. In other words, if the hemoglobin is presented with both oxygen and carbon monoxide it is 300 times more likely to combine with the CO. The result is that the blood that leaves the lungs and heads toward the body is rich in CO (carboxyhemoglobin) and poor in 02 (oxyhemaglobin).

This strong affinity of hemoglobin for CO means that very high blood levels can occur by breathing air that contains only small amounts of CO. For example, breathing air that contains a carbon monoxide level as low as 0.2 % may lead to blood CO saturations greater than 60% after only 30 to 45 minutes. So, a faulty heater or smoldering fire that produces only a small amount of CO becomes increasingly deadly with each passing minute.

This powerful attraction for hemoglobin explains how certain individuals succumb to CO poisoning in open areas. Most people believe that CO is only toxic if it is in an enclosed area, but this is simply not true. There have been cases of individuals dying while working on their car in an open area, such as a driveway. Typically the victim is found lying near the car’s exhaust. Similarly, the newly recognized problem of CO poisoning in swimmers and water skiers, who loiter near a dive platform on the back of a powerboat whose engine is at idle, is another example of this affinity.

The degree of exposure to CO is typically measured by determining the percent of the hemoglobin that is carboxyhemoglobin. The signs and symptoms of CO toxicity correlate with these levels. The normal level is 1 to 3%, but may be as high as 7 to 10% in smokers. At levels of 10 to 20%, headache and a poor ability to concentrate on complex tasks occur. Between 30 and 40%, headaches become severe and throbbing and nausea, vomiting, faintness, and lethargy appear. Pulse and breathing rates will increase noticeably. Between 40 and 60% the victim will become confused, disoriented, weak, and will display extremely poor coordination. Above 60% coma and death are likely. These are general ranges, but the actual effect of rising CO levels varies from person to person.

In the elderly and those with heart or lung disease, levels as low as 20 percent may be lethal. Victims of car exhaust suicide or those that die from fire in an enclosed room may reach 90 percent.

Carboxyhemoglobin is bright red in color and imparts this hue to the blood. When the ME performs an autopsy and sees bright cherry-red blood, he will suspect CO poisoning as the cause of death. This finding does not absolutely specific since cyanide inhalation or ingestion can also result in bright cherry red blood and tissues. Also, individuals dying from cold exposure or corpses exposed to very low temperatures may show bright red blood. Livor mortis in these situations may also be red or pink in color.

At autopsy, the internal organs in victims of CO intoxication are also bright red. Interestingly, this color does not fade with embalming or when samples taken by the ME are fixed in formaldehyde as part of the preparation of microscopic slides.

Individuals who survive CO intoxication may have serious long-term health problems. The brain is particularly vulnerable since it is extremely sensitive to oxygen lack. Symptoms and signs of brain injury can begin immediately or be delayed for several days or weeks. The most common after effects include chronic headaches, memory loss, blindness, confusion, disorientation, poor coordination, and hallucinations. The ME may be asked to evaluate a living victim in this situation if the exposure was due to a criminal act or if a civil lawsuit is involved.

Your victim would become sleepy, confused, disoriented, clumsy, and develop headaches as the level of CO in his body rose. He would finally lapse into a coma and would die if not rescued in time. Treatment is simply to remove him from the area and given him oxygen by way of a face mask and oxygen tank. If he is to be OK it should only take a few minutes to an hour to recover. He might then be normal or have any of the above long-term problems.

 
9 Comments

Posted by on March 13, 2011 in Asphyxia, Medical Issues, Q&A

 

9 responses to “Question and Answer: Can Carbon Monoxide Cartridges be Used as a Method of Murder?

  1. G

    March 13, 2011 at 1:23 pm

    In an episode of CSI NY, someone does kill with a carbon monoxide cannister used in staging foods for a photography shoot. The former ME now a CSI thought at first it was cyanide poisoning.

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  2. Laura Mitchell

    March 13, 2011 at 3:13 pm

    Would cartridges of CO going off intermittently in an abandoned warehouse be enough to result in injury death. Even though the room only has a small window, interior walls in warehouses tend to allow for ventilation. I’m having trouble visualizing this.

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    • D.P. Lyle, MD

      March 13, 2011 at 3:22 pm

      It depends on the size of the warehouse, actual amount of CO released, timeline, ventilation, and a few other things. The key point is that CO is very treacherous because prolonged exposure to even small amounts can be deadly. If someone can die from this outdoors while loitering behind an idling boat then death in a warehouse would be possible with enough CO for a long enough period of time. Doing the actual calculations would be very difficult since there are so many variables.

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  3. Allan C. Campbell, M.D.

    March 13, 2011 at 5:34 pm

    A variation on the above cases is the risk of air intakes near exhaust fumes,
    such as SCUBA tank air compressors. If an engine running the compressor
    or a vehicle parked and running nearby produces CO fumes, those can be
    taken into the compressor and expose a diver to a relatively high concentration
    of CO unknowingly.

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  4. cindybrownwriter

    March 19, 2011 at 9:30 pm

    How long might a Co2-induced coma last in a fit 65 yr. old? And having had that much exposure to CO2, is there any chance she may escape any long-term repercussions?

    Cindy Brown

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    • cindybrownwriter

      March 19, 2011 at 9:48 pm

      Oops. I meant CO🙂

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    • D.P. Lyle, MD

      March 20, 2011 at 7:59 pm

      Unless he suffers irreversible brain damage he would wake up in a few minutes to 20 or so minutes after being removed from the area and given fresh air. If he suffers significant brain damage then almost anything is possible all the way to a permanent vegetative state.

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  5. Sally Jenkins

    March 15, 2016 at 8:06 am

    Thanks for this – am planning a CO murder in my next psychological thriller.

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