Saturday, July 18, 2015

Mortis: Understanding Body Changes After Death, and How Authors Get it Wrong

Purchase No Witnesses To Nothing on Amazon
I recently had an email discussion with retired homicide detective and forensic coroner Garry Rodgers about death--specifically, about the ways writers screw up when it comes to decay. As a professional biologist, I was a bit appalled at how wrong I was personally getting some of these things. For example, I was only aware of one mortis--rigor. And I pronounced it "ri-gore" (short I.) According to Garry, not only are there FIVE mortises, but the pronunciation is on the first syllable and it's a long I (RYE-gore). 

Garry's unique background and expertise is now evident in his best-selling crime fiction. His novel, No Witnesses to Nothing, is based on a true crime story Garry was a part of in which many believed that paranormal intervention was involved. Whoa!

No Witnesses To Nothing can be purchased on Amazon and is a permanent part of our "Find a Book" page here on Murder Lab, where you can read the back cover blurb and find more links to Garry (also below.) Last, but not least, you can read an interview with Garry in which we discuss Garry's life as a criminologist, author, and blogger. So, without further delay, here's a little truth about what happens when you die and how to get it right in your novels.

Mortis: Understanding Body Changes After Death
Guest post by Garry Rodgers:

Many writers mistakenly believe there’s a precise science to estimating time of death (TOD). Although there’s a progressive process, the sequence and time intervals can widely vary and are influenced by many factors.

Mortis is the anatomical term for changes in a body after the moment of death. Medically, that’s when the central nervous system becomes unplugged and oxygenated blood is no longer delivered to the tissues, which naturally start recycling. The five types of mortis are:

Rigor –  stiffening of muscles
Livor –  settling of blood
Algor – change in temperature
Palor – change in color
Decomp – breakdown in tissue

All these mortis conditions are integral to a decomposing process. Death is a part of life and decomposition is a part of death. Just as life is not always predictable, neither is estimating the post-mortem interval (PMI) between when death anatomically occurred and when first examination of the body begins.

Death investigations work on a triangle of Body – Scene – History. It’s a holistic approach to determining cause of death (COD) and it’s the coroner’s responsibility to answer five universal questions:

Who is the deceased?
Where did they die?
When did they die?
What caused their death?
What was the means of death?

Some people are confused about the difference between cause and means. Cause is the medical reason – gunshot to the head. Means could be – homicide. Or, it could be – suicide. Or it could be – accidental.

There can be thousands of causes of death, but there are only five classifications:


How this ties into mortis is that in satisfying the five universal questions, great emphasis is placed on interpreting the body’s condition when first examined. This is where understanding the mortis process is so important and a lot of the interpretation comes from years of experience. Let’s look at each one.

Rigor Mortis is the stiffening of muscles. It’s caused by the body’s energy source, adenosine triphosphate (ATP), being depleted. With no energy left to keep the muscles flexible, they naturally go to a rigid state until another enzyme begins the breakdown of tissue and relaxation returns.

Immediately upon death, the body enters a brief period of primary flaccidity where it’s dead limp.

Depending on many factors, temperature and body mass being the big ones, the muscle stiffening begins in 1- 2 hours, setting into the eyelids, jaw, and neck. It proceeds to the limb joints and extremities after 4-8 hours and fixes in the organs in about 12 hours. Rigor releases in the same sequence and can be absent in as little as 12 hours or can stay for days, again depending on factors.

Livor Mortis is the pooling of blood caused by gravitational settling once the heart stopped pressurizing the vascular system. It’s evident by purplish-red blotching where blood is free to pool and blanched-white where pressure points restrict it. Lividity, as it’s also known, sets in between 30 minutes to 1 hour after death and ‘fixes’ in about 8-12 hours. ‘Fixing’ is the entire settling where the blood has coagulated and no longer runs free.

Algor Mortis is the change in body temperature. A cadaver will always achieve ambient temperature, regardless of time. A normal, living human’s core temperature is 36 Celsius (98.6 Fahrenheit) but the scene temperature could be anywhere. In a cold environment, the body will drop to equilibrate. In a hot environment, it will rise. Here’s where so many peripheral factors come into play. Body size. Layered Clothing. Air movement. And the list goes on. A rule of thumb is that a body will change about 1 degree Celsius per hour.

Palor Mortis is the change of color. Live humans are pretty much a reddish tinge due to oxygenated blood flowing (different tones for different races). Immediately upon death, a bluing phase occurs, following by a grey, then a white, then it can be a rainbow of colors as decomposition takes over.

Decomp, or decomposition, is not really a true class of mortis – rather it’s the culmination of the four mortis processes which leads to a breakdown of the body tissues and a return to nature.
Decomposition is a complex and unpredictable thing. There are two processes that morph into one:

Putrefaction – action of bacteria on body tissues
Autolysis – body breakdown by endogenous substances

In most deaths these two work in tandem, starting with a breakdown in internal organs which produces gas. This causes bloating and skin discoloring, as well as the foul odor from purging or ‘gassing-off’. As the muscle tissues change, the skin begins to dislodge, the joints become loose enough to disarticulate, fats become liquefied, and bones become exposed. Advanced decomp can become skeletonized, mummified, or consumed – again depending on so many factors, which all start from the mortis process.

The changes in a human’s body after death can be just as varied as their experiences in life. Biological, environmental, and circumstantial factors will shape your death, just like they’re shaping your life.

Garry Rodgers is a retired homicide detective and forensic coroner, now turned BestSelling crime writer and deadly blogger at Follow Garry in Vancouver, Canada, on Twitter @GarryRodgers1 or email him at

1 comment:

  1. Thank you, Garry. I did some research on this process for my second book, but none of the information I found was this complete. I'm sure I'll return to your post for details as I write mysteries. Thank you, Kris, for featuring Garry Rodgers on your great blog.