Murder Myths Debunked: Why Is Determining Time of Death Such a Complicated Process?

Determining time of death is a crucial element in every homicide investigation – both on and off screen. Knowing when a victim died can eliminate or incriminate suspects, often playing a key role in crime show plots. But why is determining time of death such a complicated process? And how accurately do TV shows portray this vital detail? It’s time to find out!

In this article…

• Determining Time of Death on Screen
• Deathly Basics: What Happens After We Die
• The Trinity of Determining Time of Death
• Established Methods & Forensic Experiments
• Why is Determining Time of Death Such a Complicated Process?
• Fiction vs. Facts of Determining Time of Death

Please be aware that this article contains graphic descriptions of death and decay. Reader discretion is advised.

“He died between 9:00 and 9:15”: Determining Time of Death on Screen

It’s a crime show classic: The coroner kneels beside the victim’s body and takes the temperature. After a quick glance at their watch, they confidently give the detectives a time of death – usually narrowed down to less than an hour. On screen, determining time of death is easy and leaves no room for doubt. In most cases, it’s done right at the crime scene, and without moving or undressing the body. 

But as is often the case, reality looks very different. Pinpointing the exact time of death is far more complicated, involving multiple steps and methods. And even then, the result is normally an estimated interval rather than a precise moment. Let’s delve into the details and uncover how real forensic specialists reveal when a murder took their last breath.

Deathly Basics: What Happens After We Die

While life ends with death, change certainly doesn’t. Quite the contrary: The moment we die, a chain of events begins that continues to alter our body – sometimes for years. A three-step categorization of the time after death helps break down this complex and fascinating process.

Immediate Post-Mortem Interval

When we die, our heart stops, the brain shuts down and the organs cease to function one by one. In forensic science, the time frame right after death is called the immediate post-mortem interval, lasting up to 3 hours. It is characterized by a lack of visible changes to the body. However, some internal processes are already starting: the eyeball begins to cloud, intraocular pressure drops, and subtle changes in the blood vessels of the eye can be observed.

Early Post-Mortem Interval

The immediate post-mortem interval is followed by the so-called early post-mortem interval, which lasts up to 72 hours after death. This period is the most crucial for determining time of death due to the number of changes taking place. Once death occurs, metabolism and heat production stop, causing the body to cool and gradually match the surrounding temperature. Blood stops circulating and begins to settle in the capillaries, sinking to the lower parts of the body. The entire body begins to stiffen – but we’ll get to that part soon.

Late Post-Mortem Interval

The late post-mortem interval begins immediately after the early post-mortem phase and can last for years. The pace of changes – some of them fairly drastic – depends on various environmental factors, making determining time of death during this period difficult.

At this point, our body is no longer our own and nature slowly begins to reclaim it. Blow flies and flesh flies can appear as early as 24 hours after death, followed by house flies, maggots, and a plethora of other species. 

Early decomposition typically starts within the first week. The skin undergoes greenish discoloration with distinct marbling, and the body begins to bloat. After one to two months, the bloated body cavity collapses, and the skin gradually slips away, exposing more and more of the skeleton.

When half of the skeleton becomes visible, the body enters the so-called skeletonization phase – usually two months or more after death. This final stage can take several years, eventually leaving behind only a set of bones.

The Trinity of Determining Time of Death

Now that we’ve covered the changes a body undergoes after death, let’s dive into how forensic scientists determine time of death. While various established and emerging methods support this process, three main areas usually take center stage: Algor mortis, rigor mortis and livor mortis. Sounds Latin? You’re absolutely right! 

Algor Mortis

Algor mortis – Latin for “coldness of death” – refers to the cooling of a body after death. While its assessment is often simplified in crime shows, it is actually one of the key factors when determining time of death. The drop in body temperature can give valuable clues about how much time has passed since the metabolism stopped. Many sources reference a decrease of 1.5 degrees per hour as a rule of thumb – but this can be highly inaccurate.

Several factors influence how quickly a body cools: ambient temperature, clothing, and even body weight and build can play a role. The most accurate method at this stage is the Henssge nomogram. Using rectal temperature as a key variable, it considers the surrounding temperature, the victim’s weight and various corrective elements to provide a fairly accurate estimate.

Rigor Mortis

Rigor mortis – or post-mortem rigidity – is the technical term for the stiffening of the body. When circulation and oxygen flow stop, certain chemicals that help muscles relax are no longer produced. As these substances decrease, calcium begins to build up, causing the muscle fibres to contract and stiffen.

While rigor mortis develops in all areas at the same time, it becomes evident first in smaller muscles, such as those in the face. Rigor mortis can be observed starting about 2 hours after death and is usually fully developed within 6 to 8 hours. Contrary to popular belief, the stiffening of a dead body is temporary: it begins to subside around 24 hours after death and has typically disappeared 12 hours later.

The presence or absence of post-mortem stiffening can help investigators narrow down the time of death, providing an approximate timeframe. Especially when rigor mortis is still present, it serves as a valuable indicator in determining time of death.

Livor Mortis

The last in the list is livor mortis, Latin for “bruise of death”. As the name suggests, it refers to the reddish-purple discoloration of the skin after death. Starting as faint patches that can still be pressed away during the first hours, it becomes more pronounced over time. The color changes typically become permanent 8 to 12 hours after death, meaning they no longer fade when pressure is applied.

Livor mortis may be just one piece of the puzzle in determining time of death, but it often plays a vital role in establishing whether a crime has been committed. When first responders arrive at a scene, it can indicate how much time has passed and reveal if there has been – possibly intentionally – a delay in calling an ambulance.

Established Methods & Forensic Experiments

In addition to assessing algor mortis, rigor mortis, and livor mortis, forensic experts rely on various other methods to support determining time of death.

You Are What You Ate

Stomach contents, for example, can offer valuable insights if the timing of the victim’s last meal is known. On average, a meal leaves the stomach within 2-3 hours. As a result, the presence – or absence – of undigested food can help indicate how long someone survived after eating. 

Of Bugs and Bodies

An entire scientific field focuses on bodies and insects. Forensic entomology examines insect species, eggs, and larvae to determine how much time has passed since death. And it goes even further  – unusual insect activity on or next to the body can indicate whether it was moved. However, forensic entomology only plays a significant role in the later post-mortem stages.

The Future of Determining Time of Death

Science and research are relentless, and so is forensic science. Researchers continue to improve existing methods and find new ones to assist in determining death.

Protein degradation has been the focus of researchers at the Paris Lodron University Salzburg in Austria. They have identified patterns that enable a more precise determination of time of death, narrowing it down to intervals of less than an hour.

In the Netherlands, several institutes have joined forces: Amsterdam UMC, the University of Amsterdam and the Netherlands Forensic Institute have developed a method that uses non-invasive temperature measurement and a computational model. Claiming that existing approaches are rather inaccurate, this method can determine the time of death for individuals who died within 50 hours, with a precision of 45 minutes. And there is more to come: The team of scientists is already exploring new areas for determining time of death.

Why Is Determining Time of Death Such a Complicated Process?

With so many forensic methods at hand, one might assume that determining time of death is straightforward – but that’s far from the case.

Algor mortis, rigor mortis, and livor mortis provide only a rough estimate of when death occurred. However, they don’t consider individual differences in physiology. Factors like body weight and medical conditions can influence how these changes manifest.

In addition, the environment adds yet another layer of complexity. Temperature, humidity, and UV exposure can either accelerate or slow down decomposition, making time-of-death estimates even more difficult. Fluctuations in ambient conditions – especially unknown temperature variations – can significantly impact the post-mortem changes of a body, sometimes making it impossible to confidently estimate the time of death.

In a Nutshell: Fiction vs. Facts of Determining Time of Death

With all this in mind, let’s take a closer look at the differences in determining time of death in crime shows and reality.

Is it Really a Time of Death?

More often than not, coroners on screen provide a fairly precise time of death, narrowing it down to a short interval. In reality, this is rarely the case. The unique circumstances and numerous variables involved in a homicide can make it difficult to determine the exact time of death. Instead of a specific time of death, investigators work with an estimated time window that can span several hours.

How accurate is the Time of Death?

In crime shows, the time of death is often presented as certain. While cases like this do exist, reality is usually more complex. The number of factors and variables involved often leads to a mere estimate, which can come with a margin for error. For example, an incorrectly assumed body temperature at the time of death – possibly due to a medical condition – or fluctuations in ambient temperature can affect the accuracy.

Does the Coroner Give a Time of Death Right Away?

TV coroners typically provide an accurate time of death within minutes, right at the crime scene. In reality, however, the process is much more complex: Multiple factors are considered and the body is usually thoroughly examined before an estimate can be made. A professional coroner will most likely not give away a number until much later.

Not Dead-on, But Deadly Entertaining

All things considered, the portrayal of determining time of death on screen does not fully reflect reality. However, this shouldn’t take away from the enjoyment of watching crime shows: Many other details are also exaggerated or omitted in fiction. The everyday business of forensic science and criminal investigation may not be exciting enough to fill hours of episodes, but the stories behind the cases certainly are – even if they’re embellished a bit to keep us coming back after the commercial break.