“Algor Mortis?

Algor mortis refers to the rate at which a body cools after death. This rate of cooling makes it possible to determine the approximate time of death by counting backwards the number of hours the body appears to have cooled from the time that the temperature was taken. The preferred time window for evaluating algor mortis is within the first several hours after death. Beyond that, the rate of cooling becomes less and less accurate as the body temperature approaches equilibrium with that of its environment.

The rate of cooling of the body and its significance should be evaluated carefully because the body temperature is easily affected by the physiology of the individual (age, weight, illness,) and the conditions of the environment (temperature, clothing, surface, activity prior to death). Unless any of these conditions are outstanding, a body cools very little during the first hour postmortem. After the first hour to a period of about six hours postmortem, a body will generally cool at the rate of 1.5° Fahrenheit for each hour after death. Under normal conditions, a temperature of 95.6° indicates the body has cooled 3° from normal (98.6°) and has likely been dead 2-3 hours.

The most accurate means for taking body temperature on a deceased individual is internally.
Hospitals will usually be able to provide a rectal temperature on request, if they have not done so already. At a scene, it is usually easier—and much more desirable—to take a liver temperature. This reading is accomplished by inserting a meat thermometer into the body just under the rib cage on the right side at a slightly upward angle in order to ensure the end of the thermometer penetrates the liver. After a period of about five minutes, the thermometer “bottoms out? or stops decreasing. I usually start off my external examination by inserting the thermometer, and by the time my examination is complete, the reading is complete.

Temperatures can also increase due to physiology or environment. Someone who dies with a high fever has a higher plateau from which to cool and will subsequently give a higher reading. Someone who dies in a heated bedroom will cool more slowly than someone in an unheated garage.

I recall taking a liver temperature on a man that was dead in his backyard on a hot summer day. He was directly on the ground face up and the temperature was in the 90’s with a much higher heat index. By the time I had finished the external examination, the thermometer read 100° Fahrenheit. I’ve seen even higher temperature readings, but I attributed most of those to the thermometer being in direct sunlight with the convex bezel on the end acting as a magnifying glass.

Typically the main significance of algor mortis is when the estimated result is distinctly different from the suspected timeline of the death. An example would be if a husband claimed that his wife was alive less than an hour before calling 911, but the rate of cooling in normal conditions indicated that she had been dead at least three hours. He may have simply been mistaken due to his grief, or he may have spent some time removing evidence of illicit drug use. Further questioning of the husband will ordinarily provide a reason for the disparity once he has been presented with physical evidence that conflicts with his original story.

In most cases, a person has been dead for so long that the body temperature may be so low as to be irrelevant. Fortunately for the investigator other physical observations can be made to help establish the window of death when body cooling cannot.


3 Responses to “”

  1. June 12, 2005 at 6:10 am

    Going with the example of the husband, if you have a strong suspicion that the story told to you by the husband or the officers on the scene is somewhat different to the evidence lying prone on the ground and around her, what do you do? Do you challenge the husband straight away? (And where is he – the next room? the station? the front yard?) Or do you tell your suspicions to the other police staff at the scene? Or do you just wait until someone has been assigned to the case?

    It is probably clear that I’ve learnt all of this (which is nothing 😉 off TV…

    And I’m sorry for leading you off topic, again.

  2. 2 danelle
    June 12, 2005 at 11:13 pm

    Man I love this blog.

  3. 3 Holly
    December 23, 2005 at 5:49 pm

    I’ve spent the last several years working as a nurse, and I have had my share of prepping bodies for coroner/funeral home transfer. However, I was working in a hospital 3 yrs ago and I had a deceased patient who was a 75 y/o BM–It was a Sunday &we had to wait for the coroner on call to pick up the body. Three hours later, the coroner came, and the body was still quite warm. The pupils were fixed and dilated, there was no pulse and no respirations whatsoever.I made a comment to the coroner, and he was puzzled as well. This pt had no fever or infection prior to death, and the room was of normal temp without the use of heater or AC. It was really strange! I never forgot this,guess I never will.

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