Q and A: Can My Serial Killer Make His Victims Float Face-up?

04 Jan

Q: My serial killer has predilections that make him want his (female) victims to float face up when they are found. He strangles them and then places them in the water, so they don’t actually die of drowning. Would plugging the throat or taping the mouth and nose shut (so air stays in the lungs) be a good way for him to achieve this effect? What else might work?

S.K. Davenport, Pittsburgh, PA

A: Plugging the throat or taping the mouth and nose would make little difference since there is not enough air in the lungs to cause a body to float. Virtually all bodies sink when first tossed into water. This is not absolutely universal as sometimes clothing can gather air and keep the victim afloat but for the most part they sink. They do not float again until the decay process has progressed to the point that gases have collected within the abdomen and the tissues and the body becomes buoyant. Most bodies float facedown for a very simple reason–the arms and the legs tend to fall in that direction rather than backwards so their weight keeps the body face down.

In order to make the body float he would have to do something to increase the rate of decay and since this is predominantly temperature dependent it would be best if the body was placed in warm water such as a heated pool, a Jacuzzi, or a swamp in Louisiana. Alternatively–and this is over-the-top sinister–he could inject air into the victims abdomen and chest and even the tissues of the legs and arms. If he injected enough the body would float immediately. In order to keep the body on its back, he would have to apply weights of some type that would weigh down the backside of the corpse. Maybe some large fishhooks placed deeply into the flesh and muscles with weights attached. Just a diabolical thought.


Posted by on January 4, 2013 in Asphyxia, Crime Scene, Q&A, Time of Death


12 responses to “Q and A: Can My Serial Killer Make His Victims Float Face-up?

  1. Daniel Benjamin Smith (dsmith77)

    January 4, 2013 at 10:53 am

    Ignoring the buoyancy issue, wouldn’t tying the arms or legs together behind the back of the victim help the chances of the body remaining face-up? Tying or cuffing the arms and legs together means they cannot swing forward even if the body rolled in a wave and the weight of the limbs would remain behind the back of the victim. So, is my thinking correct here?

    Also, would injecting something lighter than air into the lungs – like hydrogen gas or helium – and capping the nose and mouth cause a body to float indefinitely? As a diabolical side note, helium is inert but hydrogen gas, well, remember the Hindenburg. The cap would also have to be composed of a reasonably thick layer of material in order to keep the gas from leaking out. I have no idea what exposure to lighter-than-air gases might cause to the human body but the most likely scenario in my mind is that they could pass through body tissue and eventually escape over time.


  2. John T.Sutton

    January 4, 2013 at 6:57 pm

    Hello, I am a new crime writer from N.D. The only way I could find to ask my question was by commenting on your Blog.I am writing a book where a group of private investigators is hired by a living victim.

    My question is the following:

    If the forensics experts examine samples of the victim’s saliva and nasal mucus, what would be the duration of sperm motility ?I know it would be about 12 hours in the genital tract but I haven’t
    found any valid info about the nasal cavity and oral samples if my experts detect semen on my main character’s face.

    Thanks in advance.
    John Sutton


    • D.P. Lyle, MD

      January 4, 2013 at 7:52 pm

      John–I don’t answer questions directly on my blog but only rather through my website. There you find the instructions for submitting questions. There is a link on the main page.


  3. Teresa Reasor

    January 5, 2013 at 11:11 am

    I am glad Daniel is not one of my neighbors. Ha. As always unusual and interesting info on your blog, Dr. Lyle.
    Teresa R.


    • Daniel Benjamin Smith (dsmith77)

      January 7, 2013 at 9:43 am

      Thank you Teresa.

      Most of the time I stay quiet because I have nothing to add to the discussion but for some reason, this particular scenario has really caught my interest. I can’t explain it except that I have a lot to share. Here’s something more:

      Regarding buoyancy of the human body, the main factor is Density. (I checked this with two science teachers.) Water by definition has a density of 1. Thus injecting any gas will by definition be lighter than the water and have a buoyant effect. Gases with lower atomic weights – like Hydrogen (1) and Helium (2) – with have a greater effect but will likely leach out of the body quickly due to its many permeable membranes. Check a periodic table of the elements for atomic weights and remember that most common gases are composed of molecules of two atoms each – so Hydrogen is really 2 and Helium is really 4 (you double the atomic weight). Larger molecules will leak out slower. So take your pick: Nitrogen is basically inert but will last for months. Oxygen burns. Hydrogen explodes but will likely leach out quickly. Helium might be untraceable but will likely leach out quickly. And there are many others:

      Select Gases by Profession:
      * Argon gas is used by welders
      * Helium is used by carnival workers
      * Oxygen is used by medical professionals
      * Nitrogen is used in food packaging by butchers

      Wikipedia is useful in discovering applications of the various gases and thus where to find them.

      If I were writing this serial killer and chose to inject air into the body of the victims according to the scenario proposed by S. K. above, I would probably use Nitrogen gas. It’s plentiful, odorless, and has been used in everything from medical procedures and electronics to your local butcher. My mother had Nitrogen injected into her abdominal cavity after giving birth to my brother in the mid-80s. The gas did not dissipate for several months and she complained of how it made her abdomen bulge and feel. Medical professionals do not use this technique anymore that I am aware of.


  4. Daniel Benjamin Smith (dsmith77)

    January 7, 2013 at 10:13 am

    I also have a request for S. K. if Dr. Lyle is in agreement. Once this work is complete, can you post an update in the comments with the name of the work and where it can be purchased? Thank you!


  5. Frank Karl

    January 9, 2013 at 5:58 am

    You could just stick a sheet of Styrofoam (diabolically of course) under their clothing so they float face up. Place the Styrofoam properly and the arms and leg would dangle like sea-anchors and add to the stability. Add a floatation ring or bracelet around each wrist and the body might be stabilized to prevent wave action from rolling it over. Or you could just put them in old fashion coast guard like jackets. they were designed to float an unconscious person face up.


  6. pavornocturus

    February 5, 2013 at 9:34 pm

    I have been trying to find an answer to a similar question when I stumbled upon this blog. Any answers that can be backed up are appreciated. Here goes:

    Do people float even after expelling the oxygen in their lungs? (not drowning, purposeful expulsion)

    I need an academic journal or something. I’ve been searching and only found an astounding number of wiki and yahoo answers. Even a little direction would help.



    • D.P. Lyle, MD

      February 6, 2013 at 8:47 am

      Some people do and some don’t. Obese people in general float more easily because fat tissue weighs less than muscle and they tend to displace more water—and thus float–than do their thinner counterparts. But some people seem to naturally stay on top of the water and others have trouble.



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