Suppose you are an expert witness brought in to explain the use of algor mortis for postmortem interval estimation as it relates to an ongoing homicide investigation. Answer the following questions in essay format as though

Jamez

05 Feb 2026 • 10 min read

Instructions

1) Suppose you are an expert witness brought in to explain the use of algor mortis for postmortem interval estimation as it relates to an ongoing homicide investigation. Answer the following questions in essay format as though they were being asked of you by a defense attorney – not in back-and-forth transcription format. Ensure that you substantiate your answer with data, not just opinion.

“How certain are you that this method provides an accurate measure of time since death?”
“How can you know that you didn’t alter or destroy key evidence in the process of taking a rectal temperature reading?”
“Is this really the best method that could have been used to estimate time since death?”

· All assignments must be written in your own words and must include a reference list. Unless otherwise specified, each assignment must be no less than 500 words, not including your works cited information.

2) After completing this module, what do you feel are the 3 most important points discussed? Explain why you feel they are most important. Include in your discussion how the information from this module could be applied to either your current job and/or a future job (Crime Scene Investigator) within the forensic sciences.

3) After completing numbers 1 and 2, upload the work so I can upload number 3 which is a simple peer review of 100 words.

RUBRIC

AD MODULO 2: ALGOR MORTIS AND OTHER TEMPERATURE-BASED METHODS

· Temperature is one of the most essential variables to consider when estimating the postmortem interval in cases of human decomposition. Many of the artifacts of decomposition discussed in this course will be affected by temperature.

n In a general sense, HEAT or a WARMER environment will accelerate processes of DECOMPOSITION

n Whereas COLD or COOLER environment will decelerate them.

· In order to fully understand the impact that temperature has on the decomposition of a human body and the methods used to estimate time since death, it is necessary to first understand why temperature is important and what factors can cause a body to change in temperature after death. This module will also present an overview of the various methods that have been published in an effort to estimate time since death based on temperature changes.

· 2.1 How temperature affects decomposition

· For hundreds of years, scientists and researchers have investigated temperature as it relates to the human body. From the early invention of a necrometer used to assess death itself to the complex mathematical equations used today, numerous attempts have been made to associate temperature readings with time since death. However, very few were useful or comprehensive due to the great number of variables – both environmental and individual – that affect the ability to produce an accurate estimate.

· 2.1.1 Historic use of temperature estimation

· The earliest known documentation of using temperature to estimate time since death comes from Dr. John Davy in 1839 when he studied the deceased bodies of 10 soldiers in 1828 and 9 soldiers in 1838. During the initial autopsies, Dr. Davy discovered that the internal body temperatures under the heart and liver were higher than that of the external body surface and the ambient room temperature. This led him to the hypothesis that time since death is correlated to temperature. He further postulated that a “heat-generating process” such as a fever associated with the infection most of these soldiers had at their times of death would have caused a higher temperature at the time of death which would further affect the estimate. He published, in 1839, that these temperature observations “may enable the enquirer... to arrive at a tolerably positive conclusion, in doubtful cases of death, as to the time which may have elapsed, between the fatal event and the postmortem examination.”

· Shortly after Dr. Davy’s discovery, other investigators began researching the relationship between temperature and time since death. Drs. Taylor and Wilks studied 100 decedents between their times of death and up to 17 hours after admission to the morgue. They documented the age, body description, approximate time of death, ambient air temperature, and ambient air humidity and associated these with additional observations on postmortem body temperature at scheduled times after death. As a result of this study, Taylor and Wilks published several notable conclusions for the advancement of studies on the association between temperature and time since death. These included that “fat” bodies did not decrease in temperature as rapidly as “thin” or “emaciated” bodies and that bodies cooled “slowly and progressively” wherein they observed a plateau phase. The observation of this plateau phase in which bodies would retain much of their heat for approximately 12 hours postmortem would prove very important for future research on the subjects. Another key observation was that the environment of discovery and the clothing/cover (or lack thereof) of a body also affected the rate of temperature loss after death. They published, in 1863, that “the changes which take place in a dead body before the commencement of putrefaction, may, if accurately observed, enable a medical witness to form an opinion of the time at which the deceased died.”

· 2.2 Algor mortis and temperature change after death

· Many people define algor mortis as the postmortem cooling of the body, but this is not a completely accurate definition. Rather, algor mortis is defined as the postmortem change in body temperature until it reaches equilibrium with the environmental temperature. In many instances, defining it as “cooling” is acceptable as the human body’s normal static temperature is 98.6°F or 37°C which is often warmer than ambient environmental temperature. However, there are many factors which can affect this temperature change after death.

· 2.2.1 Conduction, convection, and radiation

· The three main ways that any object, including the human body, transfer heat and change temperatures are: conduction, convection, and radiation. By definition, conduction is a process in which the transfer of heat takes place between objects by direct contact, convection is the form of heat transfer in which energy transition occurs within a fluid such as liquid or air, and radiation is the mechanism in which heat is transmitted without any physical contact between objects. With specific regards to the human body, conduction occurs when a body is in direct contact with an object of a different temperature and the warmer object will transfer heat to the colder one. The most classic example of convection is the concept that “heat rises” due to the differences in density of the warmer air molecules as opposed to the cooler ones and is commonly employed in space heaters or the reversible directions of fans that either push down for warm air or pull up for cool air. Both conduction and convection are slow methods for heat transfer whereas radiation is often much faster. Examples of radiation for temperature change in a human body include exposure to sunlight or artificial temperature control (i.e., air conditioning).

· 2.2.2 Factors affecting temperature change

· In addition to the environmental factors of heat transfer that affect temperature change after death, there are additional variables that must be considered when using temperature to estimate time since death. These include body mass/weight, clothing or wrapping of the body, body position, and other biological factors. Some studies have indicated that the more body mass an individual has, the slower they will lose heat after death. However, other studies have shown that body size does not have a meaningful effect on time since death determination based on temperature loss. However, there is a general consensus that the more clothing or covering on or around the body, the slower heat will be lost.

· Figure 2.2.2a: A graph illustrating the difference in cooling rates between naked and covered bodies.

· Bodies that have more surface area in contact with a substrate of different temperature may be subject to a greater degree of conduction transfer than those with less contact surface area. Other health factors such as an infection causing a fever or engaging in significant physical activity before death may alter the ability to effective use temperature as a method of time since death determination. Many studies, including some of the very first to quantitatively associate temperature loss with time since death indicate that if an individual had a fever at the time of death that temperature loss is an unreliable method to determine time since death as it has been historically difficult to quantify the degree to which a fever changes the rate of temperature loss.

Figure 2.2.2b Body exposed to the elements.

· 2.3 Time since death estimation from temperature-based methods

· Factoring in a body’s potential for temperature change based on conduction, convection, radiation, body mass, clothing, body position, and other variables that may affect its temperature after death poses a great challenge to obtaining an accurate time since death estimation based on temperature. Many scientists and researchers have sought to establish a method to determine an accurate time since death based on temperature loss with varying degrees of success.

· 2.3.1 Rules of thumb

· Some of the earliest methods established to estimate time since death based on temperature resulted in very basic equations. Now better known as “rules of thumb” for estimating time since death due to their lack of ability to account for any specific variables that may affect the estimation, they have proven quite pervasive in the forensic community throughout the years. At present, though used very cautiously in forensic investigations, the common rule of thumb in use is known as the Glaister equation. An important discovery prior to the use of these rule of thumb equations was that cadaveric cooling does not follow Newton’s law of cooling. This was discovered by Rainy in 1868 with specific relation to the fact that postmortem processes such as rigor mortis and other artifacts of decomposition may affect the rate of cooling to a certain degree and, therefore, prevent it from following Newton’s law of cooling. Newton’s law of cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature.

· 2.4 Problems with temperature-based methods

· Despite many years and numerous studies attempting to produce a reliable way to accurately estimate time since death based on postmortem temperature change, very little headway has been made toward accomplishing this goal. The most statistically accurate method, Henssge’s nomogram, requires the use of rectal temperature readings taken on scene at the moment of discovery, which are not always recommended in a forensic setting. For forensic investigations, it is not considered best practice to do anything invasive to the body on scene until the medical examiner/coroner has conducted a full examination. Delaying the temperature reading until the medical examiner/coroner can take it would likely extend the postmortem interval beyond the timeframe for the nomogram to be most useful. Given that the insertion of a temperature probe into the anal cavity of a decedent would be considered invasive in many investigative circumstances, it precludes the utility of this method in many active investigations. Even if rectal temperatures were able to be utilized consistently in all investigations and taken on scene, there are still additional factors that exist as variables to an accurate reading. One such variable is the menstrual cycles of women as some studies suggest proximity to menstruation may cause fluctuation in an otherwise “normal” rectal temperature reading.

· Other methods that may remain useful such as the rules of thumb – which ordinarily would use rectal temperature readings but can be modified in current literature to use topical forehead or inter-ear temperature readings – also have difficulty with accuracy. This is because they require an accurate knowledge of the body temperature at the time of death. These equations operate under the assumption that all individuals have a “normal” body temperature at the time of death (i.e., 98.6°F or 37°C) but this is simply not always the case. Many individuals die as a result of disease processes or infections which can cause an elevated body temperature in the form of a fever. Drug use may also cause changes in the body temperature at the time of death which make using assumptions of normal temperatures more difficult.

· 2.5 Summary

· While temperature plays a very important role in the decomposition process, this module should serve to illustrate that it, alone, is not a very accurate method for estimating time since death. The premise that a dead body will seek to reach equilibrium with the temperature of its ambient environment is well documented, however the rate at which this occurs is not easily predicted or estimated. There are numerous variables that can affect this estimation including the environmental methods of heat transfer including conduction, convection, and radiation, and individual variations such as body size/weight, clothing or covering, body position, health, and drug use. Even if predictors such as Henssge’s nomogram or Glaister’s equation were to be used, caution must be exercised when obtaining the temperature readings for utility in these equations. Every effort must be made not to do anything invasive to a body on a death investigation scene and inserting a rectal temperature probe in the absence of the medical examiner would be considered such an invasive technique. Rather, it is more prudent to err on the side of general estimations based on rules of thumb as they have similar error rates within the first 12 hours after death.

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