The Five Stages of Decomposition

Maggot mass on dead pig

Following death, the human body progresses through five basic stages of decomposition. The duration and degree of each stage is largely influenced by the environment (temperature, humidity, etc.), body mass, any wrappings or coverings of the body, and obviously scavenging or other post-mortem disturbances. Additionally, submerged or buried bodies will decompose much differently than bodies left on the ground. This is what I will be referring to below. Here are the general descriptions of the five stages of decomposition:

Fresh:

The fresh stage begins immediately after death when the circulatory system (heart beating/pumping blood) stops functioning. It is during this stage that the blood will settle with gravity creating a condition known as lividity. After several hours the muscles will also begin to stiffen in a process known as rigor mortis.  The body temperature will also begin to acclimate to the environment.  Cells will begin to break down and release enzymes during a process called autolysis which can cause blisters on the skin. The anaerobic organisms in the digestive tract will begin to multiply, producing acids and gases (the source of the bad odors). This process is often referred to as putrefaction.

Bloat:

As the name implies, the gases being produced during putrefaction begin to build and will give the body a distended appearance. Gases and fluid will eventually escape through the natural orifices as the pressure builds.  As the gastrointestinal bacteria multiply and can lead to conditions like marbling which is a discoloration pattern seen in the skin. You may also see green discoloration in the abdomen areas and eventually a darkening (blackish) coloring of the skin overall as the process advances. Interestingly enough; I remember one time I was giving a lecture on forensic entomology at a college campus and after the lecture a serious looking young black student approached me. She asked me why I only showed pictures of black victims in my presentation. I was a bit taken back and briefly confused as I ran through a mental recap of the cases I presented. I finally told her that all of the victims were in fact white (Caucasian) in life but due to this process their skin darkened. It was an eye-opening experience and I made sure to describe this process more effectively when lecturing the public.

Marbeling on tissue

Active Decay:

During his phase the body begins to lose much of it’s fluids and mass (tissue) through purge and insect and/or vertebrate scavenging (coyote, fox, lion, etc). During this phase you may see very large maggot masses and notice a considerable increase in foul odors.

Advanced Decay:

This phase is the end of the active decay process. Temperatures can either speed up (heat) or slow down (cold) how quickly a body reaches this phase. The body has very little body mass and soil staining of the surrounding soils is still evident. This soil staining (from body fluids) may actually kill some of the surrounding vegetation temporarily. Maggots will migrate away from the body to pupate and flies will cease laying eggs.

Dry/Skeletal:

This phase is the last measurable stage of decomposition. The timing of this stage varies widely by environment. For example, a body in Florida in July (hot/humid) may reach this stage in a week while in the Winter in the Rocky Mountains (cold/arid) it might take months. If there is any skin left it will be leather-like and very tough. Mostly the body is reduced to bones and connective tissue. There is no biomass available for diverse insect colonization. Some beetles and adventitious insects may colonize a body for shelter or feeding on other insects and connective tissue. Over time the bones may “bleach” (turn white) with exposure to sunlight and eventually will begin to exhibit cracks after several years. These weathering cracks are distinctive and would not be confused with a fresh break (injury) unless by an inexperienced analyst.

Advanced decay stage on ribs

Knowing or describing the correct stage of decomposition is not a critical issue for most authors. However, if you plan on describing the state of the body it would be wise to give the reader a little information to justify the scene. For example, if your victim has been missing six months but still has visible tattoos on their remaining skin, reasonable readers are going to wonder how that is possible. One way to address that is through dialog. You could have one detective comment to the other about the extremely cold winter they have had and how fortunate they are that the cold weather helped preserve the evidence. Readers will give you quite a bit of wiggle room but recognizing when your timeline crosses these stages will help keep your writing realistic and your readers happy.