The time of death is a critical piece of information for investigators attempting to understand the cause of suspicious deaths. The temperature of a body can be used to estimate time of death during the first 24 hours. Core temperature falls gradually with time since death, and depends on body mass, fat distribution and ambient temperature. If the body is discovered before the body temperature has come into equilibrium with the ambient temperature, forensic scientists can estimate the time of death by measuring core temperature of the body.
The presence of rigor mortis also assists forensic scientists in determining the time of death. The body muscles will normally be in a relaxed state for the first three hours after death, stiffening between 3 hours and 36 hours, and then becoming relaxed again. However, there is considerable uncertainty in estimates derived from rigor mortis, because the time of onset is highly dependent on the amount of work the muscles had done immediately before death.
The presence of insects in a corpse is a critical clue towards estimating the time of death for bodies dead for longer periods of time. Because flies rapidly discover a body and their development times are predictable under particular environmental conditions, the time of death can be calculated by counting back the days from the state of development of insects living on the corpse.
Because the eggs take 18 hours to hatch and the first instar takes 20 hours to develop, the most recent time the eggs could have been laid was 38 hours earlier, if the larvae had just moulted. If they were old larvae, about to moult into their third instar, the most recent time of death would be 50 hours prior to discovery of the body.
Usually, time determinations would not be so easy because weather conditions are more variable, and identification of most maggots to species level is difficult. Forensic scientists usually undertake more detailed entomological work to determine time of death.
Eggs can be reared at temperature conditions corresponding to those estimated for the crime scene, to determine development rate. In rural New South Wales, in the early s, a man and a woman were shot dead in their home. The time of death was first arrived at by determining, with the help of the local telephone exchange, the time of the most recent phone call made from the house a Saturday night. The fact that the victims had last been alive on the Saturday was corroborated by a witness who claimed to have seen the woman and her two children that morning.
A suspect was interviewed about the double murder, but he had a strong alibi for the Saturday night. At this point the police turned to maggot evidence that had been collected from the dead bodies. The forensic entomologist estimated the minimum possible age of the oldest maggots among those presented to him to be four days.
Most of the appearance of a dead body over time is due to putrefaction:. Putrefaction occurs rapidly when there is excess heat, an illness present such as peritonitis where excess bacteria were already present or in an environment where external bacteria are high like a sewer.
Cooling of the body can slow putrefaction and freezing can stop it entirely. The degree of putrefaction allows investigators to roughly estimate the time of death based on this timeline but again you should note the broad the ranges of time. This is not an exact science which will make prosecutors very unhappy. Plants and insects are often used to approximate time of death. Through observation at a crime scene it is often possible to know how long a body has been there.
For example, grass that is covered by the body will slowly wilt and die. The rates by which specific species of grass die when covered is actually known and taking a sample of the grass to a botanist can give you a time of death if the person was killed at that scene or a time when the body was dumped if they were killed elsewhere.
Insects, flies specifically, rapidly infest an unprotected body and maggot formation while gross has well understood timeline that can be used to determine time of death. Taking samples of the maggots present to an entomologist bug doctor will give you time of death fairly accurately assuming the flies have access to the body immediately after death. The food found in a victim's stomach can give approximate time of death based on the degree of digestion that has taken place:.
One method for approximating time of death not listed in the table is the determination of Vitreous eye fluid Potassium concentration.
Potassium K is a nutrient in the body that helps to maintain the balance of electrical charges inside and outside cell membranes. The concentration of intracellular potassium is higher in the intracellular fluids than in the blood by up to 40 times.
After death, the amount of potassium inside and outside the cell membrane starts to equalize at a steady rate. This means that if you can get a potassium concentration reading from an intracellular fluid after death, you can pinpoint the time of death much more accurately than any of the previous mentioned methods. The vitreous fluid of the eye is the fluid most commonly used for this test if available. The results of the test are most accurate between hours after death.
The equation used to determine time of death based on a potassium leak rate of 0. The rate at which potassium leaks is not the same for all areas of the world and coroners have tables that help them establish the correct leak rate for their area.
The Vitreous Humor is a gel like fluid that composes most of the volume of the eye. You have now been introduced to the many methods investigators use to determine time of death in a victim. Now let's take a closer look at the chemistry behind some of the methods and processes just discussed. Stephanie R. Death and Kinetics. DNews YouTube In the chemistry laboratory, we can use our understanding of kinetics to both measure and manipulate the timeline of death.
Drying Blood Blood is a complex mixture of many types of cells, nutrients and cellular waste but predominantly it is water. Rigor Mortis Immediately after death all of the muscles in the body relax. In general: If the body feels warm and no rigor is present, death occurred under 3 hours before.
If the body feels warm and stiff, death occurred hours earlier. The deceased is the most valuable piece of potential evidence at any death scene. Hence, a systematic and thorough examination of the deceased should be undertaken at every death scene. Blood spillage or spatter should be noted and will remain after the removal of the body.
Weather conditions, location, and poor lighting may mask some faint injuries and trace evidence on the body, therefore the death-scene investigator should document in writing, by sketch, and by photography all information about the body that can be gathered at the scene Horswell, b.
The forensic medicine expert should focus on the physical condition of a body at a scene. Without a scene investigation, much initial, valuable body information can be lost. The following points will serve as a guide. When initially notified, a forensic medicine expert should determine as much information as possible from the caller. Approximate age and gender places a subject in a certain "medical category.
By gathering these data, a forensic medicine expert is able to anticipate additional infonnation that may be needed upon arrival at a scene Dix et al. The first rule in performing a death scene investigation is to make certain that the scene is safe and secure.
Usually, this requires police involvement but in some instances, it will require other professionals, such as fire department personnel or utility workers. The second rule is to not contaminate or disturb the scene. At the very least, death investigators should wear disposable examination gloves and it is also advisable to wear shoe covers and hair nets. Occasionally, full body covering is desirable.
When touching items at a scene, examination gloves should always be worn and care should be taken not to sit on furniture or lean against or brush against walls or furniture Prahlow, The death-scene investigator must seek answers to the following questions: is trace evidence at the scene consistent with the death having occurred at this location? Does the body contain any trace evidence that is unusual for this location, for example, mud on soles of shoes, grass, or seed material embedded in or found on the clothing when the deceased was located inside a building?
Is the death one that can be attributed to natural causes? Are there any external signs of violence? Is there anything amiss or out of the ordinary regarding the scene? Horswell, b. A successful death investigation, involving more than one individual, requires cooperation and coordination. Any potential conflicts should be worked out Dix et al.
This is not melodrama, just intellectual satisfaction for exploring an extremely important, educational, and fascinating aspect of death investigation. All death scenes should be secured and recorded photographically and diagrammatically.
If the information to hand, backed by the postmortem, suggests that the death was due to natural causes then the scene should not be processed any further. However, if there are signs at the scene, and other information suggests that the deceased died in suspicious circumstances, and this is reinforced by signs of a struggle or anything unusual, further processing for latent impressions and trace evidence should take place Horswell, b. The four major tasks of documentation are note taking, videography, photography, and sketching.
All four are necessary and none is an adequate substitute for another. For example, notes are not substitutes for photography. Documentation, in all its various forms, begins with the initial involvement of the investigator. The documentation never stops; it may slow down, but the need for documentation remains constant.
Death scene documentation will be discussed below in the sequence it should follow at a death scene. The systematic process presented will maintain the organized nature of scientific death scene investigation. Effective notes as part of an investigation provide a written record of all of the crime scene activities. The notes are taken as the activities are completed to prevent possible memory loss if notes are made at a later time.
Accurate crime scene note taking is crucial at sider the who, what, when, why, and how, and specifically include:. Notification information. Date and time, method of notification, and information received. Arrival information. Means of transportation, date and time, personnel present at the scene, and any notifications to be made. Scene description. Weather, location type and condition, major structures, identification of transient and conditional evidence especially points of entry , containers holding evidence of recent activities ashtrays, trash cans, etc.
Victim description. Position, lividity, wounds, clothing, jewelry, and identification presence or absence. Crime scene team. Assignments to team members, walk-through information, the beginning and ending times, and the evidence-handling results Miller, The forensic medicine expert should observe a great deal, but do very little.
He or she should note the position of the body in relation to nearby objects and establish the plan of the premises if indoors. A sketch or his own photograph is sometimes useful, and some forensic medicine experts use a Polaroid, digital or video camera for instant recording of the death scene. Any obvious cause of death should be observed, and any blood pools or splashes noted in relation to the position of the corpse. The shape of such splashes should be observed, as blood striking perpendicularly to a surface leaves a circular mark, whilst that landing obliquely is pear-shaped, with the sharper end towards the direction of flight.
Both natural and unnatural deaths can produce abundant blood at a scene. Traumatic deaths that involve arterial or venous bleeding, such as stabbing, can produce abundant blood at the scene with spattering. Gunshot wounds can cause extensive external bleeding, but some wounds can cause minimal external bleeding and massive internal bleeding.
In short, the amount of blood perceived at a scene does not indicate the severity of the trauma Wagner, Videotaping a death scene has become a routine documentation procedure.
Its acceptance is widespread, due to the three-dimensional portrayal of the scene and increased availability of affordable equipment with user friendly features like zoom lens and compact size.
Jury acceptability and expectation have also added to the recognized use of videography in death scene investigations. Videography of the crime scene should follow the scene survey.
The videotaping of death scenes is an orientation format. The operator should remain objective in recording the death scene. Videotaping of death scenes is a valuable tool that allows clear perception that is often not possible with the other documentation tasks. It is not an adequate substitute for any of the other tasks Miller, The purpose of still photography documentation of the death scene is to provide a true and accurate pictorial record of the death scene and physical evidence present.
Still photography records the initial condition of the scene. It provides investigators and others with a record that can be analyzed or examined subsequent to the scene investigation, and serves as a permanent record for legal concerns. Photography of a death scene is normally done immediately following the videography of the scene or after the preliminary scene survey.
A systematic, organized method for recording the death scene and pertinent physical evidence is best achieved by proceeding from the general to specific guideline. Adherence to this guideline allows orientation of the entire death scene, orientation of the evidence within the scene, and provide; examination quality photographs of specific items of evidence that may be used for analysis away from the scene.
The number of photographs that should be taken at a death scene cannot be predetermined or limited Miller, Information such as body location and unique circumstances at the death scene may help a forensic medicine expert. It is important to keep in mind the legal implications of the photographs. Will the photographs be subpoenaed? Dix et al. The scene and body are photographed before anything is moved or removed. Treat the body with respect. Never remove the clothing in full view of onlookers.
The final task in documentation of a death scene is sketching. All of the previous tasks for documentation record the death scene without regard to the size or measurement of the scene and its physical evidence. Sketching the death scene is the assignment of units of measurement or correct perspective to the overall scene and the relevant physical evidence identified within the scene Miller, The deceased's location relative to other objects and structures within the scene is very important.
The position of the deceased is plotted: the head and groin of the deceased are good points on the body to use for plotting its position. Accurate measurements should be noted to place the items within the scene in the sketch in the same locations as they appear in the scene Horswell, b.
Positive identification of the decedent is crucial in all death inquiries. The family should be notified. Information such as medical history, work, and social history can only be obtained after an identification is established. Care must be taken to insure that the identification is absolutely correct Dix et al. A systematic, thorough inspection and evaluation of the decedent should be performed by a forensic medicine expert.
The body should be prone face up during the examination, if possible. Photos of the original position of the body must be taken before the body is moved. One begins with a general assessment and progresses from head to toe, pushing clothing aside but not removing it. Some find it easier to assess rigor, livor, and algor mortis initially. The purpose of the assessment of the body at the scene is to provide some insight into the nature of the case and a working cause of death Wagner, One of the most important questions that needs answering is: did death occur at this location?
The position in which the deceased was discovered is of particular importance as it will provide an indication as to whether the deceased was moved or not before being discovered. The presence or absence of rigor mortis or stiffness of the body, whether absent, minimal, moderate, advanced or complete, will help the death-scene investigator determine if the person died at that locus in the position as found.
Some death-scene investigators with relevant training and experience may feel they are in a position to evaluate rigor mortis and hypostasis.
A pink-purple discoloration is usually present at the lowest point of the body. This is due to the settling of the blood by gravitation and the location and state of fixation should be noted and photographed. For example, unfixed livor blanches white when moderate pressure is applied, as opposed to fixed livor mortis, which remains the same color when pressure is applied. If livor mortis is noted on the deceased in areas not consistent with forming in the lowest parts of the body then the death-scene investigator should consider the possibility that the deceased was moved after death Horswell, b.
Victims may be found in contorted or apparently uncomfortable positions on the floor, commonly the bedroom or bathroom.
Generally, the more contorted the body, the more sudden the death. Bodies found in awkward positions that compromise breathing can die of positional asphyxia. The chest wall must be able to rise and fall for respiration to occur. If one is wedged too tightly in a position, the chest wall cannot rise and fall Wagner, Fig. Many inexperienced investigators focus on a major injury and neglect to evaluate the rest of the individual.
This can lead to important oversights such as fingernail marks, bruises, and. Seventy two-year-old man had lost the key of the door of his house in his vineyard and he tried to go in from a small hole which he made on the roof. He was stuck and found dead in the hole due to positional asphyxia. Documentation of this inspection should be made noting the presence and absence of unusual markings or abnormalities.
Descriptions of the state of rigor and livor mortis as well as the body temperature of a subject helps a forensic medicine expert to estimate the time interval since death. Environmental assessment, including temperature, heating or cooling systems, moisture, and wind conditions must be made at a death scene so that the environmental influence on a decedent can be determined.
The assessment should also include the types of clothing and jewelry. This information may be needed to assist in determinating the time a subject was last seen alive. Clothing should be appropriate for the weather and location found. If not, it needs to be explained. One should also determine if the clothing fits an individual.
If a subject is decomposing, then clothing may appear too small due to body swelling. If the clothing is the incorrect size, one must determine why. Was the person wearing someone else's when death occurred? Or, was the decedent redressed by another person after death? Note the cleanliness of the clothing.
A variance in the clothing or body cleanliness may indicate that he was handled by another individual after death Dix et al. General uncleanliness such as lack of bathing, very dirty clothes, urine -or feces- stained clothes, long and dirty nails, and poor oral hygiene may be due to alcoholism, drug abuse, or a mental disorder Wagner, Is the clothing worn properly?
Are buttons fastened and zippers closed? It is common to find opened zippers in intoxicated males or some elderly persons living alone. If the clothing is inconsistent with normal dressing techniques, consider whether a subject had a disability contributing to this behavior. Jewelry should be carefully noted and reported as to its type, style, color and body location.
All jewelry must be listed, regardless of its apparent value. Obvious "missing" jewelry should also be noted, such as only one pierced earring, or no wedding ring on a married individual.
Currency and credit cards should be handled as valuable items. Currency should be counted in the presence of another and credit card details noted. If an investigator decides that these items may be given to the next-of-kin at the death scene, he must be certain that the relative has the legal right to such items.
No analyses should be performed on a decedent's body at a scene, such as gunshot residue or fingerprinting, without the expressed consent of the forensic medicine expert responsible for the postmortem examination. Clothing should not be removed, a body should not be cleansed, and liquids or powders should not be placed on the deceased as these might interfere with radiographs or chemical testing. If more than one hour has elapsed since the initial body assessment and the decedent is still at the scene, a second assessment should be recorded.
Generally, there is no correlation between facial expressions, body positions, and suffering. Pain and suffering can be assessed before and during the dying process, but it is done carefully and generally by the forensic medicine expert after evaluating the autopsy and investigative information. This information can be useful to the family, and can become arguable in civil court cases Wagner, An investigator must also gather information that relates to cause and manner of death.
Each type of death requires specific scene information. For instance, questions to be asked in a motor vehicle fatality would not be the same as those asked in an autoerotic asphyxia death.
Since different questions need to be asked, an investigational guide for each specific type of death can be very useful. For example, it is critical in suicides resulting from a handgun that investigators determine the handedness of a subject Dix et al. The scene should be searched for a medical history in nearly all death investigations.
This search may be as simple as finding an inhaler for asthma nearby a gunshot wound victim or as complicated as going through cabinets full of medication at a residence. Many people do not take the treatments the doctor ordered and reject advice given at the hospital. Only interviewing witnesses and searching the scene will reveal this information Wagner, Prior to a forensic medicine expert's arrival, law enforcement officers, paramedics, and other support personnel probably have communicated with individuals or witnesses at the scene.
A forensic medicine expert needs to know this initial information so that he can compare it with the decedent's body data and determine if there are any discrepancies. It is better to ask the question twice and get the same answer, than to accept as fact information that has been checked by one source. A forensic medicine expert needs to determine, for instance, if the body data rigor, livor, temperature, clothing, injuries, etc.
Forensic medicine experts and law enforcement agents work cooperatively in a team effort. Although the medical expert has jurisdiction over the body, law enforcement has jurisdiction over the entire scene. The forensic medicine expert is invited to the scene and, as a guest, must comply with house rules.
In Britain, for example, several teams converge on a scene of crime, including photographers and video operators, and Scene of Crime Officers SOCOs whose function is to collect trace evidence. Scientists from the nearest forensic laboratory often attend with their police liaison officers, as well as fingerprint officers and, of course, the investigating officers from the Criminal Investigation Department.
The lead detective will walk the forensic medicine expert through the scene, relaying information and pointing out salient features. Where no such backup is available, the forensic medicine expert must try to collect trace evidence himself, but he should remain within the limits of his own expertise. The forensic medicine expert should accept the instructions of police officers in relation to the approach to the body so as to preserve the immediate environment as much as possible.
Out-of-doors access is often limited to a single pathway marked by tapes, and in a building a track to the corpse is usually pointed out by the detective in charge. The doctor should not touch anything unnecessarily and certainly not smoke or leave any object or debris of his or her own.
The Locard Exchange Principle states that whenever two objects come into contact, a mutual exchange of matter will take place between them. Linking suspects to victims is the most important and common type of linkage accomplished by physical evidence in criminal investigations. Linking victims and suspects to objects and scenes can also be accomplished by use of the physical evidence Miller, Fig. The year-old murderer killed his employer in his workplace as he did not pay his salary.
On the death scene investigation, a horror mask on the top and footprints of sports shoes of the murderer on the bottom were found.
These evidences were used to determine the murderer. After surveying the overall death scene, it should be easy to recognize the sequence in which evidence is to be collected and areas to be searched and in what order. The collection and search should be systematic, ensuring absolutely nothing is overlooked. In establishing the manner and sequence of collecting potential evidence by death scene investigators, consideration must be given to the possible destruction of evidence and which approach will yield the best result in terms of useful information Horswell, b.
Clues about the cause and manner of a death and who committed a crime may be found at a scene. The following list includes different types of evidence and how they are usually collected and preserved. Blood - Dried particles should be scraped into a drycontainer. Some dried areas may be sampled with a wet swab. A specimen should be dried before sealing it in a container. Articles of clothing or other objects containing blood may be submitted to a laboratory for sample removal by a technician.
Semen - An article of clothing containing semen should be collected or the specimen on the clothing can be lifted with water or saline. Fingerprints - Soft objects that leave an impression may be collected in their entirety. Prints on hard objects like glass or furniture should be lifted at the scene.
Firearms and other weapons - These should be submitted to a lab without special treatment at a scene. A technician must ensure proper handling so that fingerprints are not smudged or ruined. Bullets and cartridges - These should not be grasped with metal forceps because points of comparison may be damaged.
Hairs and fibers - These should be placed in separate containers and should not be crushed with hard objects such as metal tweezers. Suspicious foods and pills - Each item should be placed in separate containers or bags to prevent contamination. Footprints and tire marks - At the scene, casts should be made and close-up photographs should be taken.
Tool marks - There should be close-up photographs of the marks made by tools and, if possible, the damaged material should be removed for analysis by a lab technician. Blood spatters - These should be photographed and described for analysis as to distance and angle of spatter. Samples may be removed for testing and preservation. Other - Glass, soil, documents, cigarette butts, tobacco, and all items thought to be involved in arson should be collected and submitted to a lab.
Each item submitted to a lab should be referenced by either a photograph or written description as to its location in the scene. All containers with items submitted to the lab must be labeled on the lid and side of the container, with a case number, date, time, type of specimen, and name of the person who collected the specimen.
A "chain of custody" begins at this point and continues until a disposition of the specimen is completed Dix et al. Methods of searching critical areas include grids that are larger in less critical areas and smaller in critical areas, or searching in a clockwise or counterclockwise direction from a fixed point, or conducting a line strip search.
All these form part of conducting a professional systematic search of a death scene. A systematic approach to the searching of death scenes reduces stress and fatigue and ensures a more comprehensive search and recovery operation, minimizing the chance of losing potentially valuable evidentiary material Horswell, b. Any weapon or other item possibly related to the death and found at a scene should be brought to the morgue for analysis by a forensic medicine expert.
Often, substances are the causative agent in the death. All medication and alcoholic beverage containers should be confiscated as these will be invaluable to the toxicologists. Note the location where each item was found.
Studies have shown that a fatal intoxicant is likely to be found in the same location as a decedent. Any drug paraphernalia, notes, or any unusual item that might have been used by the subject should be confiscated Dix et al. Interviews should include basic information such as the subject's identification, clothing, time, date, state of health, date and time the body was discovered, and medical, employment, and social history.
Any recent events that may have a bearing on the death are also important. A death investigator should always ask if a decedent had recently been involved in any potential harmful situations. This information may be extremely helpful if later attempts are made to make a prior incident a contributing factor in the death.
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