Estimating the Time of Death: Algor Mortis

Algor Mortis is the last of the three Cardinal changes occurring to a body following death. The other two, Rigor Mortis and Livor Mortis have been covered before on this blog. Algor Mortis is the postmortem cooling of the body. Technically, it’s the acclimation of body temperature to the environmental temperatures. The healthy human body in life maintains a temperature of about 98 degrees Fahrenheit (37 degrees Celsius). If the air temperature is lower the body will cool and if the temperatures are higher then the body will warm. Typically these measurements are taken by inserting a probe into the liver (at least twice with an hour between).  Oral temperatures are not reliable examples of core body temperatures and are not used.

There are a number of things that can affect how quickly the core body temperature acclimates.  Some of those conditions include the type and amount of clothing the victim is wearing, or if the victim is wrapped (like in plastic sheeting). Bodies with a lot of clothing will be more insulated from the environment and thus cool more slowly. Body mass also influences temperature change. Environmental temperatures obviously influence this process and some areas see dramatic swings in temperatures in short periods of time. My readers in Colorado are very familiar with this. We can have a white-out blizzard in the morning and have clear skies and 50 degrees F by lunch. If the clothing or wrappings are wet then that will have an influence as well, especially when temperatures swing between freeze and thaw.

Adding to all of these considerations is the realization that decomposition is not a static process. Scavengers (vertebrate and arthropod) can significantly alter coverings and body mass at unpredictable rates. Over the years, scientists have attempted to develop various formulas to estimate the time since death using changes in core body temperature. However, due to the variations experienced during decomposition these formulas are not considered reliable.

As an author, you should probably avoid having characters put too much emphasis on Algor Mortis estimations or readings unless you want to set your characters up to be in error. This can be a useful tool, especially if the character you want to “set-up” is not directly involved in the forensic sciences (like a hospital pathologist or family doctor). You could create some tension between the police, victim’s family, and a hospital pathologist using an over-reliance on postmortem body temperature levels. Your Coroner/Medical Examiner or entomologist character will most likely be able to settle the issue with finality and use other postmortem changes to estimate the time since death.

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About forensics4fiction

Hi there. Thank you for visiting my BLOG for crime writers. I hope you will find it interesting. I would love to hear your questions and thoughts regarding forensics and criminal investigations. I hope that the information here will help answer your questions or ignite your imagination. I am a retired senior criminalist with 15 years of forensic experience. I have served as the president of the Association for Crime Scene Reconstruction, Rocky Mountain Association of Bloodstain Pattern Analysts, and the Rocky Mountain Division of the International Association for Identification. I am triple board certified in forensic related fields and one of only 40 board-certified bloodstain pattern analysts and 80 board-certified footwear examiners worldwide In addition to writing over 60 scientific papers, I have worked as the editor of the Journal of the Association for Crime Scene Reconstruction, been interviewed by and consulted for television, books, magazines, and newspaper articles including documentaries on the Discovery Channel and National Geographic.

Posted on November 25, 2011, in The Autopsy and tagged , , , , , , , , , , , , , , . Bookmark the permalink. 6 Comments.

  1. Are you able to tell me when the “idea(s)” of rigor/algor/livor mortis were essentially “created” ? If that makes sense

    • Sure Jennifer, I’m not sure of the exact earliest time these changes were observed and scientifically documented but references in my library go back to the 1830′s. Not a typo, early 19th Century. Back then rigor mortis was referred to as stiffening or cadaveric rigidity and forensic pathologists recognized it’s association with temperature and time although I don’t know of any detailed studies. References discuss the issue in a matter-of-fact way leading me to believe that it was common knowledge among professionals. Lividity was called lividity and algor mortis was referred to as “coldness” and (as today) not a very reliable time indicator.

  2. Thanks! This was really helpful! :D :D :D I love mysteries and homicides, and this has really boosted my research! I`ll be sure to read the rest of your posts, too!

  3. With a degree in forensics how long would it take to become a forensic nurse? I have seen that this is a new and promising branch of forensics.

    • Forensic nursing is a very competitive field. It really depends on the market. More jobs are obviously available in the bigger hospitals but there is also more competition for those jobs. There are a couple forensic nursing organizations that may be better suited to offer advice on the best approach and which markets (parts of the country) are seeing any bursts in hiring. Good luck!

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