Estimation of Death Time

Abstract

Death time is an issue that is generally requested to be determined by the prosecution offices that request autopsies. The determination of the time of death may be necessary for the heirs to carry out some legal actions and also, from a forensic point of view, to enlighten the case. Although its determination is very important, there is no known scientific method by which the exact time of death can be determined. Generally, the ambient conditions where the corpse is found, the environmental temperatures, and similar factors are evaluated, and the time interval is estimated by considering these factors according to the level of algor mortis, livor mortis, rigor mortis, signs of decomposition or skeletonization. The estimated death time is then reflected in the autopsy report. In this section, we aim to explain in detail how we make these estimations according to the time intervals and environmental conditions, as well as to review the literature in this area.

1. Introduction

Today, there is no method that can be used alone in the determination of the time of death [1]. It is noteworthy that most of the proposed methods do not have a standardized procedure [1, 2]. Therefore, the term “time of death” should be avoided even if all factors are taken into account [3]. However, it is possible to determine the approximate duration of death as “interval” [3]. The usage of methods such as algor mortis and electrical stimulation of muscles either as isolated methods or in multi-methodological approaches was introduced as reliable in the estimation of early postmortem intervals (PMI) [4, 5]. Along with the physical methods, the usage of biochemical parameters in combination with other parameters were reported to be beneficial [6]. In the journey of scientific advancements. Degradation of nucleic acids over time stands at the attention-grabbing point in the field of PMI estimation [7, 8]. However, in this chapter, we will be focusing on how to estimate the death time during the postmortem external examination in practice by using the factors as postmortem changes and if present phases of decomposition.

2. Usage of postmortem changes in the estimation of death time

2.1 Usage of algor mortis in the estimation of death time

Postmortem body temperature is considered normal at the time of death. There may not be a significant increase or decrease in natural and rapid deaths and forced deaths in postmortem body temperature [9]. In some cases (such as congestive heart failure, massive bleeding, and secondary shocks), the temperature may be subnormal, and in deaths from infections, pons bleeding, and heart attacks, it may be above normal, and in some cases (septicemia, fulminant infections, etc.), it may continue to increase for a few hours post mortem [10].

The use of postmortem interval determination methods based on body temperature is limited due to their high standard deviations [5, 11]. Although there are many schemes used in dead cooling, none of them is completely reliable, and the most useful of these schemes is the Henssge Normograms, with which the estimated time differs from the real time by 2.8 hours [4].

2.2 Usage of rigor mortis in the estimation of death time

After death, the body muscles first relax, and after this event, which is called primary muscle relaxation, stiffness of muscles becomes visible in about 1–3 hours, which is called rigor mortis [12, 13]. There are also cases where it has been reported that rigor mortis occurs within 15–20 minutes [12, 13, 14]. It takes approximately 6–12 hours for the rigor mortis to become visible throughout the body [12, 13, 14].

The formation of muscle stiffness depends on the consumption of ATP available after death and the lack of new ATP production. ATP is the main energy source required for muscle contraction [12, 14, 15].

The development of stiffness actually occurs in all muscles at the same time; however, it first appears in smaller muscles such as the jaw muscles, so it is said that rigor mortis starts from small muscles and gradually spreads to the whole body [12]. The onset and duration of dead stiffness are closely related to muscle mass and functional state before death [9]. There are many factors such as ambient temperature, physical activity before death, and so on, which affect the formation of dead stiffness [16]. Therefore, PMI cannot be determined by only looking at the rigor mortis parameter. While interpreting PMI during the onset and end of rigor mortis, symptoms such as cooling of the corpse, condition of dead spots, and decay should be evaluated together [9]. Rigor mortis disappears with decomposition in about 36 hours depending on the ambient conditions, but it can be seen to extend up to 6 days [12, 14]. In very hot environments, it can be seen to disappear within 24 hours [14]. Regarding the determination of rigor mortis and PMI, there are experiments in which Kromprecher measures rigor mortis at certain hours [17]. In the study by Hirakawa et al. with Nuclear Magnetic Resonance Spectroscopy, metabolic changes in the femoral muscle of rats after death were examined, and it was reported that the data obtained showed hourly differences, and these differences were correlated with PMI [17].

2.3 Usage of livor mortis in the estimation of death time

Since circulation stops with death, the vascular system and blood physiology completely change. Components in the blood remain under the influence of gravity due to the cessation and immobility of blood flow [12, 18]. Under these conditions, the plasma and cellular contents precipitate, initially forming a sediment within the vascular system of the corpse [19]. Later, it gradually collects from the vascular system into venules and capillaries near the ground, with the effect of gravity, and over time, dark purple and sometimes light red “livor mortis” occur on the skin parts of the corpse that are close to the ground that do not have pressure on [12, 14]. About 30 minutes after death, dead spots that start to form in a period of about 8–12 hours become fixed according to the body position; in cooler environments, it may take 24–36 hours for the dead spots to become fixed [14]. Livor mortis can be seen until the body completely loses its color due to decay [13].

2.4 Usage of postmortem macroscopic changes in the eye in the estimation of death time

Many methods have been proposed for the estimation of the postmortem interval based on the changes in the eye [15].

About 10 minutes after death, the cornea becomes cloudy. If the eyelids remain open in dry weather, the cornea will turn brown in a few hours. At the 10th or 12th hour, the cornea takes on the color of milk. The complete formation of corneal opacity takes the third day [3, 9].

Measurement of intraocular pressure with the tonometer method, which is stated to be used up to the postmortem 6th hour; direct examination of retinal blood vessels with ophthalmoscope; and reflex contraction due to electrical or pharmaceutical stimulation of the iris may be possible in the early postmortem period [15].

It has been observed that reflex contraction can occur with injections of localized catecholamine solution for up to 46 hours following clinical death [15].

Jafaar and Nokes state that eye-related changes such as corneal opacity, retinal vessel segmentation, pupillary reaction, retinal changes, and intraocular pressure changes seen in the postmortem eye can be used in the early detection of PMI [20].

In the study by Kocaturk et al., no relationship was found between pupil diameters and tache noire development and PMI, but it was reported that the rate of corneal clouding was statistically significantly higher (P < 0.01) if the postmortem period lasted longer than 8 hours [3].

There is also one other method that uses the excitability of orbicularis oculi found to be reliable, which tests the local contraction and not the whole muscle [4].

2.5 Usage of postmortem stimulations of nerves and muscles

It was first revealed by Professor Luigi Galvani in 1780 that isolated muscle groups can be stimulated by external electrical stimulation [15].

In the determination of PMI, there are subjective and objective measurement methods that examine the changes in skeletal muscles due to postmortem stimulation [4]. Henssge and Madea visually evaluated the muscle response to stimulation and showed that the accuracy of their predictions increased when they used the heat method together with their method [4]. The same researchers also made objective measurements with muscular power conductors placed in the muscle [4]. There are studies in which the peripheral nervous system is also stimulated for the determination of PMI [2].

3. Usage of decomposition in the estimation of death time

Decomposition is a process consisting of autolysis and putrefaction [14]. Autolysis refers to aseptic chemical destruction processes of cells and organs by the help of the intracellular enzymes [14]. Since this is a chemical reaction, it accelerates with temperature, slows down with cold, and stops with freezing [14]. Organs rich in enzymes are autolyzed faster than others [14]. For this reason, the pancreas autolyzes faster than other organs [9].

Bacterial fermentation: After death, the flora in the gastrointestinal tract disperses throughout the body, creating putrefaction [14].

Although the putrefaction varies according to the environmental conditions, it starts with a green color change in the right lower quadrant approximately 36–48 hours after death, and the stage progresses until the skeletonization [9, 14]. There are four phases of decomposition [9].

3.1 First phase of decomposition in the estimation of death time

This period is the beginning of decay; it varies according to ambient conditions. It starts with green coloration of the skin over the cecum, in the right lower quadrant, approximately 36–48 hours after death [9, 10]. Epidermal separations and bulla formations are observed. The gases released as a result of decay are approximately 60–72. It causes the abdomen to begin to swell within hours [14]. The abdomen appears swollen and tense within a week; in conditions where the environment is very hot, swelling can occur in 24 hours, and in very cold environments such as Siberia, putrefaction does not occur even for thousands of years [14]. In common sepsis cases, there are cases where decomposition is observed to accelerate even if the corpse is immediately placed in the refrigerator. It is stated that even if a septic corpse is placed in the refrigerator, it can appear as 5–6 days old within 6–12 hours [14].

In the 3rd and 4th weeks, as the gas and volume increase in the corpse reaches its maximum dimensions, the abdomen bursts [9, 12]. It is thought that this period is completed in approximately 3–4 weeks (1 month) under average conditions of 15–20°C [9, 12].

3.2 Second phase of decomposition in the estimation of death time

With the realization of the explosion in the abdomen, the abdomen and chest wall collapse [9, 12]. All organs look like sacs filled with a mud-like substance (9). After this period, the evaluation of PMI becomes difficult and varies greatly according to conditions [9, 12].

3.3 Third phase of decomposition in the estimation of death time

The liver becoming indistinguishable indicates the beginning of the 3rd period. Muscles gradually begin to separate from their places [9].

3.4 Fourth phase of decomposition in the estimation of death time

When gender becomes indistinguishable from the outside, it is considered to have entered the fourth stage [9]. Depending on the characteristics of the environment in which the corpse is buried, the muscles and joints are separated within a year or two [9, 12]. Although it is not certain, skeletalization is completed in 3–5 years on average, depending on conditions such as soil drainage [9, 12].

Along with the PMI estimation methods made by looking at the postmortem changes in the first hours after death, the stages of decay with the onset of decay and entemological examinations can also be used to determine the time of death in later periods [9, 21].

The use of entomological evidence in the determination of PMI has been known for a long time [9]. Bergeret was the first person to use data on entomofauna in funerals by conducting forensic medical examinations on corpses [21]. After Bergeret, many more comprehensive studies were conducted using the results [21].

There are studies to determine the time elapsed after death and the place where death occurred by examining the changes made by insects on the corpse and the development level of insects [21].

4. Role of biochemistry in the estimation of death time

Studies continue on the use of biochemical analyses in PMI determination [22]. The biochemical parameters studied are hypoxantin, Ca + 2, ammonia in vitreous fluid; K + in the vitreous and cerebrospinal fluid; serum nonprotein nitrogen (NPN); cerebrospinal fluid amino acids; and blood pH [23]. In addition to the convenience of taking blood samples, it is also possible to compare them with pre-mortem values [23]. Another tissue that can be easily sampled and examined postmortem is vitreous fluid [23]. However, since the pre-mortem values are not known, there is no possibility of comparison [23].

Macromolecules and enzymes circulating in tissues with blood circulation, such as glucose, insulin, and alkaline phosphatase, may show quantitative differences between the right and left chambers of the heart as there is no postmortem circulation [23]. For this reason, it is necessary to know the exact place where the blood sample was taken. Taking blood directly from the heart is never recommended, instead, it is generally recommended to use venous samples [23].

Kominato et al. investigated the conversion of a complement factor (C3) to its constituent fragments in the blood for the determination of PMI by immune electrophoresis and suggested that there was a statistically significant correlation between C3 degradation and PMI, and thus, it was reported that PMI could be predicted by looking at the C3 fragmentation rate [24]. Endo et al. measured monoamine metabolites in the cerebrospinal fluid and observed that the concentration of 3–4 dihydroxyphenylacetic acid increased with time after death and reported that it could be used in the determination of PMI [25].

In the study conducted by Doğan et al., it was found that the use of Fe, K, Na, Ca, and Cu elements in rat tissues could be reliable in determining PMI; significant changes were reported in more than one tissue at 4°C and 18 ± 2°C in line with the passing time after death, which needs to be supported by other studies and on other tissues as autopsy tissues [26].

We have recently seen the usage of DNA and RNA degradation in PMI estimation as innovative approaches [27, 28] However, all these studies were evaluated as preliminary that reflects the early phases of the subject where we predominantly see the usage of animal models, containing a lot of uncertainties and depending on various extrinsic and intrinsic factors as environmental conditions, causes of death, and so on [27, 28, 29, 30, 31].

5. Estimating the death time during the postmortem examinations

5.1 Why do we try to estimate the death time?

The methods mentioned in the above-mentioned literature generally remain as methods that are not used much in practice at the experimental level [1, 2, 3, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]. However, the question of the exact time of death remains on the documents pertaining to the autopsy request made by the prosecution offices.

For every answer to be stated in the autopsy report for this question, it should be emphasized there is no specific scientific method that can give a definite result on this subject. Subjective and empirical estimates can be made about the time of death in the form of intervals, and the estimates obtained in the form of time intervals they receive from us will need to be supported by forensic investigations [1, 2, 3, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31].

5.2 How do we try to estimate the death time?

5.2.1 Things to be recorded before the postmortem examination

The most important point we should pay attention to in estimating the time of death is that the progression of the postmortem changes that we will use toward decomposition and from decomposition to skeletonization accelerates with higher temperatures, slows down with cold, and stops with freezing [12, 14, 16]. At this point, whether there are personal underlying factors (such as infectious diseases, sepsis, etc.) that may accelerate the progress toward decomposition in the corpse, the air temperatures, and the ambient temperatures where the corpse is located should also be taken into account and recorded [9, 10].

5.2.2 Things to be recorded during the postmortem examination

Postmortem changes should be recorded in particular detail in order to be able to estimate the time of death during the external examination of the cause of death before the autopsy [9, 12, 14]. The items to be recorded can be listed as follows:

1. The temperature of the corpse (rectal temperature) [9].

2. It should be carefully examined and recorded whether rigor mortis, which start to become visible primarily in small joints such as the jaw joint after primary muscle relaxation after death, spread to all muscle groups in the whole body and whether the dead stiffness is resolved. It should be taken into account that dead stiffness may not be observed in joints where the dead stiffness is dissolved by force, and this should not be confused with the onset of decay [9, 12, 13, 14].

3. It is important to record whether livor mortis occur or not, and if they do, whether they are fixed or not so that we can estimate the time of death [12, 13, 14].

4. If there are signs of decay, at what level they are, whether they are in the form of early signs of decay in the form of greenish discoloration in the abdominal region and the epidermal separations, whether the abdomen is swollen, or whether there is abdominal burst [9, 10, 12, 14].

5. If skeletal remains are brought, whether there are tissue remains on the bones [9, 12].

5.2.3 How do we estimate the time of death after the postmortem examination?

5.2.3.1 If the corpse is still warm?

In cases where the cooling of the dead is not felt yet, and if possible determined that the dead cooling of the corpse has not progressed by rectal measurements, it is important whether livor mortis and rigor mortis have occurred [9, 12, 14].

A still warm corpse without dead stiffness and livor mortis is usually encountered in hospital deaths where the moment of death is known; however, in this case, it would be a more appropriate behavior to check the time of death from the medical records.

If we encounter such a corpse at the crime scene where it is found dead, then it can be said that what we have done is a subjective and empirical estimation and that the death occurred within a maximum of 3 hours backward from the time of the postmortem examination [9, 12, 13, 14].

Similarly, in a warm corpse, dead stiffness is not yet observable in large joints, and in cases where livor mortis have just begun to be observed, it can be noted that death can be estimated to have occurred at least 3 hours and at most 6 hours before the time of the postmortem examination, and this given time frame is based on subjective estimations [12, 13, 14].

5.2.3.2 If the rigor mortis can be seen throughout the body?

In a corpse where the rigor mortis is visible throughout the body, it is important whether the livor mortis are fixed or not [12, 13, 14]. When some pressure is applied to the postmortem lividity, if there is a fading in the area where the pressure is applied or a change of place of the postmortem lividity is observed by changing the position of the corpse, it can be said that the death took place at least 6 hours before the time of the postmortem examination, and the livor mortis become fixed in 24–36 hours in cold environments according to the ambient temperature [9, 12, 13, 14].

It should be noted that if there is a corpse with dead stiffness and fixed livor mortis, it can be estimated that the death occurred at least 12 hours before the postmortem examination, and this estimation is not certain [9, 12, 13, 14].

5.2.3.3 If there are signs of decomposition?

In a corpse where the solidity of the dead has been dissolved, signs of decay become important. The signs of decay are usually noticed by the greenish discoloration of the lower abdomen and the dissolution of the rigor mortis [9, 10, 14].

Considering that the onset of decomposition in average conditions (at temperatures between 15 and 20 degrees) is 36–48 hours, in a corpse encountered in cold winter conditions and in which the signs of decay are new, death is roughly within a period of at least 48 hours before the postmortem examination [12, 14, 16]. It should be noted that in summer conditions, it can be said that a maximum of 48 hours have passed from when the postmortem examination was performed, and in hot climates and if the corpse has an underlying disease such as sepsis, the signs of decay may begin within 6–12 hours after death [9, 12, 14, 16].

In average conditions, within the first week of death, epidermal separations, together with the swelling of the abdomen and the marbling phenomenon are observed [9, 10, 14]. Although it is noted that swelling in the abdomen can be seen within 24 hours in very hot conditions, it would not be wrong to say that the death occurred within a period of at most 1 week backward from the time of the postmortem examination in a case where the abdomen is swollen and tense and there are widespread epidermal separations throughout the body [9, 12, 14, 16]. If such a corpse is evaluated at ambient temperatures below 15 degrees, it can be said that at least 1 week has passed since its death [9, 12, 14, 16].

At this point, the expressions “minimum” and “maximum” that we will use while specifying the time period also vary according to the air temperatures and ambient temperatures [9, 12, 14, 16]. For example, it can be said that the death of a corpse with widespread epidermal separations, which we see in 15–20 degrees and hotter conditions; dead stiffness resolved, and extremely tense and swollen abdominal region has occurred within a maximum of 1 week. It can be said that at least 1 week has passed from the time of the death.

It should be noted that when we encounter a corpse with widespread signs of decomposition in the abdomen, at most 1 month has passed since death at temperatures of 15–20 degrees and above, and at least 1 month ago at temperatures below 15 degrees; our estimation is an average estimate [9, 12, 14, 16].

5.2.3.4 Estimation by found bones

In this regard, it may be preferable to perform laboratory tests, if possible, rather than external examination [9]. If we are still asked to make an estimation, an estimation can be made based on the condition of the bone remains. Considering that the skeletonization is completed in 3–5 years on average, the presence of tissue remains suggests that death may have occurred in a time period of at most 3 years, and the completion of the skeletonization without any tissue residues on the bone tissues suggests that at least 3 years have passed since death [9, 12].

5.2.3.5 Estimation by insect activity

The presence of insect eggs in areas such as the nasal and oral cavities does not constitute a very important parameter in determining the time of death, because these eggs can also be seen especially on immobile and debilitated individuals [9, 21].

Time of death can be determined according to the developmental level of insects [9, 21]. This can be achieved by entomological examination of the samples taken during postmortem examination.

Thanks

I would like to thank first my elders in Muğla for being a reason for me to live in Muğla for a while and to my colleagues and the staff of the Muğla directorate of Forensic Medicine Institute, with whom I have worked in harmony for 7 years for their friendship and for the autopsy practice they have added to my adventure in forensic medicine.