Decomposition Rates Slow with Increased Blood Loss

By:  Darren Dake, D-ABMDI, CI, CCI

I was recently asked a question concerning decomposition rates when the body has suffered significant blood loss. I have to admit; I didn’t completely know the answer.

Throughout my career, I had seen examples of what appeared to be slower rates of decomposition when a death occurred in such a way that an extreme amount of blood had left the body at or reasonably soon after death, but with so many other environmental factors it was not much more than just an observation.

However, after being asked this question, I started doing some research and found an article written by Seth Augenstein of Forensic Magazine. In his article, “More Blood Loss, Less Corpse Decomposition” Augenstein summarizes a study on the subject and offers insight from the authors of the study. What follows is an excerpt of his article. Click on the link below to read Augenstein’s article in its entirety.

By correcting for variables including the indoor or outdoor location, age, weather, and other factors, their statistical analysis found that the more blood that is lost, the slower and less completely a body rotted.

“The results suggest that increased blood loss may retard the progression of decomposition,” writes Diane Cockle and Lynne Bell the two authors from Simon Fraser University in British Columbia.

The study’s original dataset contained 7,300 cases of discovered corpses. From that total Cockle and Bell narrowed down to 341 cases, mostly from British Columbia and Ontario, because of the thorough collection of data and photographs collected from the scene. Decomposition was scored for each body on a scale from 0 (no visible signs of decay), up to 8 (total skeletonization).

About half the cases (47.5%) showed notable degrees of blood loss: 17.9% with minimal loss, 20.5% with moderate, 5.9% extreme and 3.2% total exsanguination.

The causes of death were also catalogued: 21.4 percent featuring blunt force injuries, 15.4 percent with ballistic wounds and 14.3 percent with sharp traumas.

The 46 variables such as height and weight, age, environment, debris on the body, coverings, insect activity, and even ante-mortem drug and alcohol ingestion were factored in—and the outliers were identified and eliminated using multivariate stepwise regression analysis.

More blood loss was linked to decreased decomposition, across the board, they reported.

The study showed possible explanations included the bounty of blood’s content—humidity, proteins, amino acids, waste, and a huge variety of other materials that may accelerate breakdown. But in blood’s absence, mummification may be promoted, and with a delay in breakdown processes.

“From a taphonomy standpoint, significant blood loss represents a clear inhibitor of bacterial transmigration from the gut into the post mortem blood supply and may help explain the confusing variance reported for intra-environmental contexts for terrestrial exposure, and usefully for indoor decomposition too,” write the investigators.

The other three major factors in decomposition rates were: post-mortem interval in days, alcohol use, and insect activity.

However, one other theory did not bear out in the data. Previous studies of death processes surmised that the openings of wounds might present better access for insects, and thereby boost decomposition rates. The authors could not find proof of that in their findings.

However, the presence of blood—or lack thereof—was a consistent factor in the decay of death.

“The results from this study underscore the importance of considering the impact of blood loss on human decomposition,” the pair concluded. “This information may assist death investigators with the knowledge that extreme blood loss may contribute to the deceleration of decomposition and possibly an increased period of tissue preservation.”

Cockle said that her years of death investigations had posed questions about decomposition rates. For instance, a multiple murder in the same house at the same time involving two different causes of death could show significantly different trajectories of decay. Cockle, who is an RCMP staff sergeant, said she wasn’t solely looking at blood loss, but at all the factors she could find that may cause different decomposition rates.

“I was looking at all the variables,” she said. “Because of my experience as a crime-scene investigator, I thought (these) could be variables—so let’s check them out.

“One potential upside is that crime-scene personnel could realize that bodies with exsanguination could potentially remain at the scene longer, with less of a risk of advancing decomposition prior to autopsy,” Cockle said.


Augenstein, Seth, “More Blood Loss, Less Corpse Decomposition”, Forensic Magazine, 05 December 2018.  Accessed 24 April 2019

Cockle, Diane L., Bell, Lynne S., “The impact of trauma and blood loss on human decomposition”, Science & Justice, Volume 59, Issue 3, Pages 332-336, 2018.  Accessed 24 April 2019