In this blog post, we will take a look at the role of forensic science in revealing the truth through the last evidence left by a dead body.
It is natural for a person to die. However, when a person dies in a way that is incomprehensible to others, those around them begin to question the death and try to find out the reason. Death is a fate that we all cannot avoid, but when the process is unclear or abnormal, we naturally want to find the reason. This is a natural human reaction, and it is also a social and ethical responsibility to uncover the truth of death.
A long time ago in Korea, on February 4, 2001, two naked bodies were found in the Deul River in Naju, Jeollanam-do, one week apart. Forensic science came into play and revealed the truth through various traces left on the body. The body of the victim, Park Yang, showed both signs of strangulation and drowning, which indicated that she died by being strangled underwater. In addition, the DNA of the suspect’s semen was found in Park Yang’s body, indicating that she and the suspect had sex. Forensic techniques such as DNA analysis provide clues to the case and play a crucial role in tracking down the perpetrator. However, the role of forensics goes beyond simply finding the perpetrator. It is an important tool for maintaining the dignity of life and revealing wrongful deaths. However, this was not evidence that she had actually committed murder. Forensic experts found clues to the murder in the unusual state of the semen of the suspect and Park’s menstrual blood, which were not mixed in Park’s body. Normally, semen and menstrual blood are mixed when a person moves, but they do not mix after death because the deceased does not move. This allowed us to determine that Park Yang died shortly after the sexual intercourse. These subtle clues are very important because they can often determine the outcome of a case. As the Duddle River murder case shows, forensics has evolved beyond simple scientific analysis to become an academic discipline that clearly distinguishes and interprets human life and death.
As can be seen in the Ddolgang murder case, people show various phenomena after death depending on where and how they die. These phenomena are called postmortem phenomena, and postmortem phenomena refer to various changes in the body that occur in accordance with the laws of nature as vital activity ceases immediately after death. Typical examples of such phenomena include the body becoming stiff or the body color turning dark reddish. These changes clarify the boundary between life and death and provide important clues for estimating the cause of death and the elapsed time after death through forensic analysis. By analyzing when these phenomena occur, we can solve the mysterious deaths around us. Nowadays, there is a shortage of forensic experts compared to the increasing number of suspicious deaths, so in this article, I will look at the scientific principles of these corpse phenomena to increase the general public’s understanding of forensic evidence. I will also focus on the bloat and sag, which are the main clues to the cause of death among the corpse phenomena.
As soon as a person dies, breathing and blood circulation stop, the complexion turns pale, the muscles relax, and the pupils dilate, and the pupillary reflex disappears. This state can be called cardiopulmonary arrest, as the heart has stopped, but some cells in the body are still alive and continue to function for a period of time. During the progression from cardiopulmonary arrest to complete biological death, typical corpse phenomena such as cyanosis, rigor mortis, decreased body temperature, drying, and decay occur.
The phenomenon of cadaverization can be divided into the initial cadaverization, such as a decrease in body temperature, blood subsidence, cadaver stiffness, and drying, the terminal cadaverization, in which the body decomposes or collapses, and the abnormal cadaverization that occurs under special conditions, such as the half-ossification, mummification, putrefaction, and cadaveric infestation that also occurred in the body of Yu Byung-eun. These postmortem changes are not simple postmortem changes, but the result of the body interacting with the environment after the cessation of vital activity. This allows forensic scientists to estimate the cause of death and time of death, and furthermore, to clarify the entire story of the incident. The reason for analyzing these postmortem changes is to estimate the postmortem elapsed time and cause of death. And when analyzing postmortem changes, interference can always be a factor, so it must be taken into account.
Interference refers to “any findings that may interfere with the diagnosis or forensic interpretation of the cause of death, whether during or after the person’s lifetime.” A common example is interference caused by cardiac massage and the use of automated external defibrillators. In the case of cardiac massage, this can cause bruising on the chest and multiple rib fractures. In addition, using an automated external defibrillator can cause subcutaneous bleeding or skin abrasion around the nose and mouth, and acute pneumothorax. And these signs are likely to be misinterpreted as a cause of death. Therefore, forensic scientists must carefully analyze these interference phenomena and take care not to misunderstand the nature of the incident. Forensics is a discipline that requires precision and accuracy, so clearly distinguishing interference phenomena can be an important key to uncovering the truth of an incident. Therefore, when making a forensic interpretation, one must always keep in mind that interference phenomena may be involved.
The first thing to address is blood pooling, which is the phenomenon in which red blood cells are collected along the blood vessels due to gravity in the outer skin or the lower part of the viscera when a person takes a certain posture for a certain period of time after death due to the blood circulation stopping. The location of the formation of the shivans, their color, and the stage of occurrence can be used to determine the postmortem interval and cause of death. Analysis of the shivans can be the first clue at the scene of death and is used as important data to determine whether the body was moved or died from another cause. First, the position of the shivans changes depending on the posture of the body. Shivans form on the nape of the neck, back, waist, and back of the limbs when the body is lying down, and on the face, chest, stomach, and front of the limbs when the body is lying down. If the blood is highly fluid, shivans may also appear on the side of the body, but they do not appear on the parts that are under pressure. For example, if a body is lying on a gravel road, only the parts of the body that are pressed by the gravel will not show a blue discoloration. Second, although the body continues to breathe after death, the CO2Hb formed in the blood is not excreted, so the body generally has a dark red color. However, the color of the blue discoloration may vary depending on the cause of death. If the person dies in a cold place or is left in a cold place after death, or if the cause of death is drowning, carbon monoxide, or cyanide poisoning, the sclera appears bright red. If the cause of death is potassium chlorate or nitrite poisoning, the sclera becomes brown as methemoglobin is formed. If the cause of death is hydrogen sulfide gas poisoning, the eyes turn green as sulfide methemoglobin is formed. This change in the color of the eyes is an important factor in estimating the cause of death and in some cases it can provide clues to the crime. Third, the bruising appears 12 hours after death and is fully formed after 6 to 12 hours. Between 12 and 24 hours, moving the body causes blood to move to other areas and a new bruise forms, but after 24 hours, the blood is fixed and moving the body does not change the location of the bruise. Finally, the intensity of the bruising is generally an important criterion for estimating the elapsed time after death. Initially, the bruises appear only on the surface of the skin, but over time, they become deeper and become fixed bruises that do not change color even when pressed after 12 hours. These characteristics of bruises allow forensic experts to estimate the time and place of death and are used to determine whether the body has been moved or to determine the posture at the time of death. This is an important clue in criminal investigations and plays a crucial role in determining the cause of death.
Dying blood clots form when the heart stops beating, causing blood to no longer circulate and pool in the veins and capillaries. Therefore, the appearance of a clot can be used to estimate the elapsed time since death. Clots appear 12 hours after death and are fully formed after 6 to 12 hours. If the body is moved within 12 to 24 hours, the blood will move to another area and a new bruise will form, but after 24 hours, the blood will be fixed and the location of the bruise will not change even if the body is moved.
The second type of rigor mortis, also known as cadaveric rigidity, refers to the phenomenon of the muscles of the body becoming stiff after death. As the muscles stiffen and the body hardens, the location and strength of the rigor mortis can be used to estimate the elapsed time after death. Rigor mortis is an important indicator for tracking the passage of time after death, and it can be used to accurately estimate the time of death. First, the rigidity is used to estimate the elapsed time after death by determining where the rigidity starts and progresses. The rigidity starts in the facial muscles and then progresses sequentially to the jaw, neck, arms, and legs. When complete rigidity is reached, the body becomes very hard. After 3 to 4 hours, the facial muscles begin to stiffen, and after 12 hours, the entire body stiffens, resulting in complete rigor mortis. The state of complete rigor mortis lasts for about 18 to 36 hours, after which the muscles relax and the body returns to its relaxed state. This process may vary somewhat depending on environmental factors, temperature, etc. For example, decomposition progresses faster at high temperatures and slower at low temperatures. Therefore, by analyzing the extent and location of decomposition, forensic scientists can more accurately estimate the time of death, and this information plays a very important role in criminal investigations and accident investigations. Second, the intensity of decomposition is used as an important indicator for predicting postmortem elapsed time. Initial rigor mortis appears relatively weak, but over time the muscles become more rigid, and after 12 hours the whole body becomes rigid. This state lasts for about 18 to 36 hours, after which the body begins to relax again. Finally, the loosening of the rigor mortis provides a clue to more accurately estimating the postmortem interval. Generally, the decomposition process starts from the lower part of the body and progresses to the upper part, and this process takes about 24 to 48 hours. This process of decomposition provides important clues related to the time of death and is one of the important methods used by forensic scientists to analyze the condition of the body. In addition, the strength and location of the decomposition are sometimes used to estimate the situation at the time of death or the posture of the body. For example, if the state of the body found and the intensity of rigor mortis do not match, it is possible to consider the possibility that the body was moved after death. Rigor mortis does not simply indicate rigor mortis after death, but acts as an important key to elucidate the cause and time of death and the full details of the incident.
In addition, there is a drop in body temperature during the decomposition of a corpse, which refers to the gradual decrease in body temperature after a person’s death. A living being with a normal body temperature cannot produce heat after death, and its body temperature gradually decreases to match the temperature of the environment. Body temperature plays a very important role in estimating the time of death, and this allows forensic scientists to more accurately determine the time of death. The body temperature begins to drop 23 hours after death, dropping by 1-2 degrees in the first hour, and then gradually slowing down over time. This may vary depending on the ambient temperature, the condition of the body, and other factors, and an analysis of the body temperature drop that takes these variables into account can be an important clue in solving a case. Usually, the difference between the ambient temperature and the body temperature of the deceased can be used to estimate the elapsed time since death.
It is natural for a person to die. However, when a person dies in a way that is incomprehensible to others, those around them begin to question the death and try to find out the reason. Death is the inevitable fate that we all face, but when the process is unclear or abnormal, we naturally want to find the reason. This is a human instinctive reaction, and it is also a social and ethical responsibility to uncover the truth of death. This sense of responsibility further highlights the importance of forensics, and forensics experts are constantly striving to uncover the truth of death. Forensics is more than just the application of scientific knowledge, and it plays an important role in achieving social justice and uncovering unjust deaths.
