Crime Scene Investigation Notes PDF

Topic-1 [Crime Scene Investigation?] CSI generally combination of various elements. - Searching - Preliminary Examination - Collection - Preservation - Documentation Principle and Law Of Forensic Science - Law Of Individuality: Anything and everything involve in a crime, has...

Topic-1 [Crime Scene Investigation?] CSI generally combination of various elements. - Searching - Preliminary Examination - Collection - Preservation - Documentation Principle and Law Of Forensic Science - Law Of Individuality: Anything and everything involve in a crime, has an individuality. - Principle of Exchange: When anything come in contact of anything they leave traces. - Law of Progressive Change: Everything changes with the passage of time. - Law of Comparison: Only the like can be compared. - Law of Analysis: The analysis can be no better than the sample analysed. - Law of Probability: All the identification definite or indefinite are made consciously or unconsciously, on the basis of probability. - Law of Circumstantial Fact: Facts do not lie, human can do. History of Forensic Investigation **[Mathieu Orfila (1787 -- 1853)]:** (Father of Forensic Toxicology)was a Spanish-born toxicologist and chemist and the founder of the science of toxicology. **[Francis Galton (1822 -- 1911)]:** His most significant contribution was distinguishing fingerprints with similar patterns. He realized that fingerprint ridges never repeated, even in twins. Thus, accurately identifying individuals required comparing the minutiae of fingerprint ridge details. **[Alphonse Bertillon (1853--1914)]**:(Father of Criminal Detection) the son of medical professor Louis Bertillon, was a French criminologist and anthropologist who created the first system of physical measurements, photography, and record-keeping that police could use to identify recidivist criminals. **Albert S. Osborn (1858 -- 1946)**:(Father of Questioned Documents)A key figure in the development of document examination principles, he authored the seminal treatise \"Questioned Documents\" in 1910. His efforts were instrumental in establishing the credibility of documents as scientific evidence in court proceedings. **[Leone Lattes (1887-1954)]**(Father of Bloodstain Identification) emerged as a prominent figure in both medico-legal and general serology during the first half of the twentieth century. His early involvement in blood grouping marked(A, B, AB or O) a significant contribution to the field. **[Edmond Locard (1877 -- 1966)]:** Principle of exchange. **Calvin Goddard (1891 -- 1955):**(Father of Ballistics) The pioneer of ballistics, renowned for his groundbreaking work, utilized a comparison microscope to ascertain whether a bullet originated from a particular firearm. Furthermore, he conducted a seminal study on \"tool marks\" found on bullets, further solidifying his legacy in the field. CSI Terminologies - CSI - Evidence - Searching - Collection - Preservation - Documentation - Chain of Custody - Report - Court Testimony Role & Scope of CSI Office - Secure the Crime scene from further contamination. - Apply best searching method. - Documentation of Crime scene (Sketching, photography, Videography, 3D Scanning). - Collection, Preservation & Preliminary testing. - Go to court for expert testimony as an when it require **Topic 2**\ Securing and Searching the Crime Scene [Scene of occurrence] A scene of occurrence is the site where the incidence or crime has occurred. It is the meeting place of the persons involved. The parties exchange traces with one another and with the scene, leave odds and ends and marks of tools, wearing apparels, means of transport, hands and feet. Thus the scene of occurrence provides a wealth of information which is useful to: - 1\. Establish corpus delicti - 2\. Provide link between the criminal, the victim and the scene of occurrence - 3\. Evaluate the pattern of events - 4\. Indicate modus operandi, sequence of events - 5\. Help reconstruction - 6\. Provide leads - 7\. Indicate number of culprits, weapons [Problems] The examination of the scene of occurrence should help to establish: 1. How did the criminal and the victim reach the scene ? 2. What were the routes of entrance and exit? 3. How many criminals and victims were involved? 4. What was the modus of operandi? 5. What evidence did the criminal and the victim exchange.? 6. Is the alleged scene of occurrence genuine or simulated ? 7. When was the crime committed ? 8. Why did the victim behave in a particular way? 9. Who were the criminals or victims ? 10. Whom did the criminal visit after the occurrence ? LOCATION The scene of occurrence is located from the following: 1. Accounts of eye-witnesses 2. Marks of struggle 3. Corpus delicti 4. Abandoned articles, impressions and prints, bloodstains and stains from other body fluids. For example, a stain of ejaculated semen, once, established the site of rape 5. Traces carried over from the scene. For example, once, the plant fragments on the clothes of a child indicated the place of assault. It is not difficult to locate the scene of occurrence, but sometimes criminals simulate a scene to mislead the investigators. Evaluation Proper evaluation of the scene of occurrence is a time consuming job. It involves the following: 1. Protection 2. Photography/Videography/3D Scanning 3. Sketching 4. Search 5. Handling clues 6. Recording 7. Modern aids. Protection The investigating officer cannot always reach the scene immediately after the occurrence. The first police official who reaches the scene, therefore, should be careful to preserve the evidence: 1. He should check the injured body or bodies for any signs of life. Even if there is at remote chance of life, medical help should be called in immediately and the injured transported to the nearest hospital. These steps are taken with deliberation and caution so as to disturb the scene to the minimum extent possible. If the injured are already dead, the scene is left undisturbed. 2. All unauthorized men: relatives and friends of the victim or of the culprit, onlookers, photographers and media persons should be excluded from the scene. They are handled carefully, politely, persuasively, yet firmly. 3. The scene of occurrence should not get altered. It should be barricaded whenever possible, enclosing rather a larger area than a smaller one so that no clues are possibly left out. 4. 4\. Suspects and witnesses should not be allowed to discuss the case with one another. If the culprit is positively identified he should be arrested. If there is only suspicion he should be detained. If he tries to run away, he should be arrested. 5. 5\. Fellow policemen (including the senior officers) should be requested not to enter the scene to satisfy their curiosity. Only the officer-in-charge of the case should determine when, why and who is to enter the scene. 6. 6\. The officer assisting the investigating officer, should not start independent searches and inquiries. He should do what the officer-in-charge tells him to do. 7. 7\. Assistance of other police officers and Forensic CSI team should be requisitioned at the earliest, whenever necessary. 8. 8\. The police officer should not leave the scene of occurrence unguarded. 9. 9\. The name of the informant with his address & number, the time when he gave the information and the alleged time of occurrence should be recorded. 10. 10\. The officer should not discuss the case with the suspects, the complainants, the victims, the witnesses, the onlookers or the pressmen. 11. 11\. The officer should not introduce any material, like cigarette ends, cigarette ash, foot or footwear marks or fingerprints at the scene. 12. 12\. The doors, windows, stair-cases, lighting, routes of ingress or egress should be preserved in their original condition till the examination is finalized. 13. 13\. The officer should record the time of his own arrival, note and record the weather conditions. Alcohol, tobacco, perfumes and explosives give distinctive odours. Record them, if they are noticed at the scene. 14. 14\. The officer should not use the utilities: bathroom, wash basin, lavatory, towels, telephone, etc., at the scene of occurrence. 15. 15\. He should not move anything from its place. It has to be described and its location fixed by sketches and photographs 16. 16\. The scene even if it is in a mess, should not be cleaned till thoroughly examined. Alteration of positions of objects is permitted in emergencies only. Record the change if it is made. Searching Zonal Method Spiral Method a. Inward b. Outward c. Strip Method: d. Cross-Hatch Search Method: Equipment's - DSL Camera: - Videography Camera: - 3D Camera: Leave no detail behind provides high-resolution imagery for crime scene reconstruction and evidence collection. - Body worn camera. - Drones CSI KIT(List all items of kits) Foot & Tyre Casting Kit (List of items provided) Fingerprint Kit **KIT CONTENTS:** - Black Powder - Black Magnetic Powder - Dual Use Magnetic Powder - Fluorescent Blue Magnetic Powder - Fluorescent Orange Magnetic Powder - Fluorescent Yellow Magnetic Powder - Fluorescent Red Magnetic Powder - Clear Lifting Tape - Mini Scalpel Cutter - Fiber Brushes - Feather Brush - Magnetic Brush - White Lifting Cards - Black Lifting Cards - UV Lamp9200 Mobile testing kits. - Biological Fluids - Drugs - GSR - Explosive - Arson - Gas Detector Evidence packaging Kit (List of items provided) Topic 3\ Recording the crime scene [Recording] The three most common methods of recording a crime scene are: note taking, sketching, and photography. But due to advancement in technology now a day videography and 3D scanning of crime scene is also added for better representation of crime scene. A detailed record of the crime scene and of the actions taken during the search of it, help the crime scene expert to accurately recall events and to identify items of evidence later in a court of law. Notes Note taking is one of the most important parts of processing the crime scene. It forces investigators to be more observant; when writing things down, people frequently remember details that may otherwise be overlooked. Notes should be complete and thorough, written clearly and legibly. They should detail step-by-step every action that the investigator takes and the order in which it is taken. The investigator should measure the scene and refer to these measurements in describing all evidence and where it was found. Notes should include the date and time; a description of the location, weather, and environmental conditions; a description of the crime; the location of the evidence relative to other key points; the names of all people involved, including authorized personnel, witnesses, and victims; all changes that have occurred; and any other relevant information. Sketching Before beginning a sketch, obtain a comprehensive view of the scene. Determine the sketch limits -- decide what to include and what to exclude. If the scene is complicated, a number of sketches may be necessary for adequate documentation. a. Overview sketch b. Elevation sketch c. Exploded view or cross-projection sketch d. Perspective sketch e. Co-ordinate method. f. Polar technique. **Overview sketch:** consists of a bird's-eye-view or floor plan sketch of the scene. This is the most common type of sketch and consists of items on the horizontal plane b**) Elevation sketch:** portrays a vertical plane rather than a horizontal plane. Examples include bloodstain patterns on vertical surfaces such as walls or cabinetry and bullet holes through windows. **c) Exploded view or cross-projection sketch:** consists of a combination of the first two sketches. It is similar to a floor plan except the walls have been laid out flat and objects on them have been shown in their relative positions. **Perspective sketch:** Depicts the scene or item of interest in three dimensions. It is the most difficult sketch to create and requires some artistic skill **Co-ordinate method:** The technique is most frequently used. A focal point is chosen and two lines crossing each other at right angle are drawn. One line (x) represents the length and the other (y) the width of the scene to be covered. The location of the objects is then filled by determining the positions of the objects with reference to their co-ordinates. Polar technique. Polar technique is used for large outdoor scenes. Here instead of drawing co-ordinates, the distances and directions of the evidentiary objects are noted with reference to a central (focal) point. The positions are recorded on the sketch accordingly. Crime Scene Photography There is an old saying that \"a picture is worth a thousand words.\" Photographs can capture details that even the most observant investigator may miss. Before making any detailed examination and before touching or moving any evidence, the investigator should photograph the scene. He or she should give special attention to points of entry and exit. Photographs help the investigator and witnesses remember details; they show where evidence is placed in the scene, and sometimes they help the judge and jury visualize the crime scene The investigator should take photographs that clarify the scene, close-up photos of evidence, photos of the scene as viewed through the eyes of a witness, and photos of the location of the scene and its surroundings. Several photos of the same object may be taken from different angles to provide different perspectives and perhaps new details. All photographs should include a ruler for scale and be carefully documented and kept as evidence. - To record the crime scene - To record the evidence(Ruler/Scale must be included in all closeups) - The evidence which we can not pick examine with the help of photographs). - It help in reconstruction of crime scene and help judiciary to understand the crime scene in more better way. Evidence handling and sampling The next step in processing the crime scene is to collect and package the evidence. The investigators must put each item collected in a separate container or package, and then label it. This helps protect the item and avoids any contamination. The most fragile evidence, such as fingerprints, bloodstains, and other trace evidence, is collected and packaged first. If evidence is found sticking to a larger object, for instance blood or hair on a piece of clothing, the whole garment is collected, packaged, and sent to the laboratory. Generally, pill bottles, vials, manila envelopes, and plastic bags are good containers for most evidence. There are some special considerations: - Wet items must be dried before packaging to prevent mold and mildew. - Containers should be sealed tightly to prevent leaks or breakage. - Biological items should be dried and kept in a freezer. - Clothing with trace evidence (such as a hair) should be packaged carefully to avoid disturbing the evidence. - Firearms should be fixed rigidly inside a wooden container. - Evidence from a suspected arson should be kept in an airtight container so that fumes from an accelerant cannot evaporate. - A collection may be made using adhesive tape to pick up the evidence. This method, however, picks up everything, not just the traces associated with the crime. - A vacuum cleaner with a special attachment is sometimes use but it, too, picks up everything. Topic 4\ Collection of Crime Scene Evidence [Preservation] Contamination of physical evidence can occur at the crime scene during collection, packaging and transportation, which may affect outcome of the analysis negatively. Therefore, it is the prime duty of the investigating officer that evidence found at crime scene must be preserved properly, so that they remain in their original state. After required examination they may be produced in the court in the condition in which they were found. The investigating officer should take all necessary steps to preserve evidence from following factors. a. From Loss b)From Damage c\) From Contamination d\) From Tempering **From Loss**: Micro traces such as dust, hair fibers, paint flakes, vegetations, etc. may be lost during packaging. If these exhibits are not properly packaged and sealed, the particulate matter may be lost through corners of the envelop. If the container is not airtight and impermeable then volatile liquids such as alcohol, petrol, diesel and kerosene may evaporate. **From Damage or Deterioration:** Malaysia is situated in humid climatic zone, therefore, biological exhibits such as blood, semen and other body fluids may deteriorate rapidly. Therefore, processing of such exhibits should always be quick. Evidence like fingerprints, footprints, shoeprints, tyre marks even bloodstains found at the outdoor crime scene must be protected properly and collected before temperature sun rays or wind destroy them **Form Contamination:** The issue of contamination of physical evidence has painfully brought in notice to several cases. The level of contamination risk to be expected is related to the type of crime scene and corresponding number of individuals who have access to it. Environmental conditions may also play a major role in the contamination of crime scene evidence. Wind can carry in contaminates due to transfer of hair, fibers and biological fluid from other place to the exhibit. if evidences fibers not properly packaged it may become contaminated by the introduction of foreign matter into the packaging. **Form Tempering:** If exhibits are not packaged appropriately and securely, they may be intended to destroy. The investigating officer therefore should not leave them unattended. For example if a firearm, fired cartridge case and bullet are left unattended and unguarded against innocent tempering, may reach at the laboratory with several impressions on the firing pain, percussion cap and bullet surface. General Precautions: In order to preserve evidence from loss, tempering, contamination and damage, the following precautions should be adopted during handling them: - As the investigating officer often travel from one place to the crime scene, the risk of transferring hairs, dust, fibers and biological fluid is quite obvious. Therefore, he should wear proper clothing and gloves. - Micro traces such as hair, fibers, broken glass pieces, paper bits, etc. should always be handled with a rubber tipped forceps. - Clean spatula, probe or spoon should be used for collection of biological materials such as blood, semen, vomit and other body fluids. Glass spoon appears to be more suitable to collect chemicals and corrosive liquids such as acids and alkalis. - Flat objects such as pieces of wood, iron or glass sheet should always be handled by the edges. - Tumblers, bottles, phials, water drinking glass and other similar objects or utensils may contain fingerprints on them, therefore, should be handled by touching finger at the top and bottom. - Weapon with sharp edges such as knife should be handled with the tip of index finger ensuring that no evidence is destroyed. - Firearm should be lifted with finger held at the tip of the butt and bare. It should not be picked up shoving a pencil into the barrel as often Shown in detective films. This practice may alter the markings on the inside surface of the barrel. - Fresh or wet blood or bloodstained clothing should not be packaged in an airtight container as evidence may be spoiled due to putrefaction. - Fired bules, pellets, empty cartridges, wads, etc. should be picked up with rubber tipped forceps. - Micro trace evidences such as dust, pollens, saw-dust etc. metal-dust are very little and it may be difficult to see them. Such powdered substances should be collected with a soft brush on a clean white paper. - Explosives and live bombs should not be handled before the clearance from the Bomb Disposal Squad (BDS). They should be handled carefully after becoming sure that there will be no explosion by normal handling. - Documents should always be lifted with the help of rubber tipped forceps. - Cut stained part. - Dry in shadow and air. - Cut a control sample. - Package all materials separately. - Large bloodstained items should be packaged in clean paper. - Small samples should be placed in plastic phials. - If blood is wet, for large amount, suck up liquid blood with a disposable pipette and then package. - For small amount of blood, rub a small piece of cotton on the stain. - For dry blood, if amount is large, scrape into a small hard plastic container using a scalpel. - Small amount of blood can be collected by rubbing a piece of moistened cotton on the stain. - Control sample can be obtained by rubbing a piece of moistened cotton on unstained surface. - All the collections should be packaged in plastic or glass phials after air drying, if wet. - Take color photograph of stains and their pattern. - Collect articles having stains. - Allow stains at air dry - Packed in paper bag or paper envelope. - Collect on clean white gauze wearing a pair of gloves. - Allow to air dry. - Packed in rigid plastic container. - Collect with plastic tweezers. - Store with folded paper and package in paper envelope or plastic bag. - Collect and preserve whole object such as clothing, bed-sheet, blanket, etc. - Wrap with clean paper and package in large paper or plastic bag. - Take color photograph with details. - Remove from suspect over a clean large white paper. - Allow clothing to air dry. - Separate trance materials if found on clothing and package in a paper envelope. - Place each article in a separate paper bag. - Collect with plastic tweezers. - Do not fold the document. - Package in a paper envelope or plastic bag with a piece of cardboard. - Collect with plastic tweezers, if object is fixed and package in paper fold. - Collect wholes the movable object containing fibers and package in plastic bag. - Use the tape lifting technique, if required, then package in a plastic bag along with glass sheet. - Wrap firearm with tissue paper/Cotton and package in a plastic bag. - Wrap live cartridges, cartridge shells, bullets and distorted projectile fragments in clean cotton by lifting with plastic tweezers and package in small plastic bags separately. - Never mark on firearm or ammunition. Label the container instead. - Bullets or projectiles recovered from dead body should be allowed to air dry before packaging. - Take color photograph, if visible. - Collect possible residues using adhesive SEM stubs/on cotton of HNO3 sol. - Take reference sample. - Take color and black and white photograph at right angle with a proper scale. - Wipe the bitten area of skin with clean cotton moistened with distilled water. - Allow cotton to air dry, then package in a plastic phial. - If possible, make a cast of bite mark and store in a small rigid plastic container. - Collect 60-70 individuals from the above, below and within the decomposed dead body. - Collect possible number of the same form surrounding and hidden areas beneath leaves, floorboards, soil, etc. - Collect pupae found in the form of brown capsules under the body or soil. - Store all the above specimens in 70% ethyl alcohol in distilled water. - Package flat articles bearing fingerprint in a plywood board-box keeping the surface untouched with anything whatsoever. - If article is not flat, cage it between two boards by string or wire. - Thermocol may be used in place of perforated plywood boards. - Take black and white photograph with proper scale. - Make plaster of Paris cast. - Package the cast on a board with thick cotton pads tied with string and place in large card-board box for further examination. - Take overview, midrange and close-up black and white photograph with proper scale. - Make a plaster of Paris cast. - Store the cast in rigid plastic container with proper packaging of thermocol. - If object is portable, then recover it for further proceedings. - Take photograph of the wire and surroundings. - Protect cut ends of the wire. - Make marks on ends cut for collection at the crime scene. - Package the wire in plastic bag. - Take photographs from both sides before removing from the window, doorframe or the vehicle. - Collect fragile fragments first. - Wrap each fragment to protect edges separately. - Collect small and large debris from the place of fire or arson. - Cut up large object in to small and package them in PVC bags. - Collect control sample from the scene and package separately in plastic bag. - Collect materials having smell of inflammable in air tight plastic bag to restrict vaporization. - Drip - Splash patterns - Flow - Pools - Serum - **Drip stain:** A drip stain is formed when blood from a wound or an object drops on a surface. - **Splash pattern:** A splash pattern is formed when a volume of blood spills onto a surface. - **Flow pattern:** A flow pattern is caused by the directional movement of blood on a surface due to gravity. - **Pool:** A pool is a bloodstain formed by the accumulation of blood on a surface. Pools are formed when a large volume of blood collects on a leveled surface. - **Serum stain:** A serum stain is formed when serum (the liquid portion of the blood) separates after coagulation. These stains are almost transparent with a reddish color around the boundary. Transfer Blood stains A transfer bloodstain is created when a blood-bearing surface comes in contact with another surface, leaving an impression on the previously unstained surface. Transfer blood stains can be further divided into: - Contact Pattern - Swipe Pattern - Wipe pattern - **Contact pattern:** A contact bloodstain is formed when a bloody object comes in contact with a previously unstained surface, without any movement. The edges of a contact bloodstain are clean and usually look like a bloody impression has been stamped on a surface. - **Swipe pattern:** A swipe pattern is formed when a blood-bearing surface in motion comes in contact with another surface that was previously unstained, thus, leaving a smudged impression - **Wipe pattern:** A wipe pattern is formed when an unstained object passes over a pre-existing wet blood stain and alters its appearance. Projected blood strains Projected bloodstains are created when a volume of blood is deposited on a surface under a pressure or a force that is greater than the force of gravity. Projected blood stains can be further divided into: - Impact pattern - Cast-off pattern - Expiration pattern - Arterial sputter - Void pattern - **Impact pattern:** An impact bloodstain pattern is a type of bloodstain pattern that is created by the force of an object, such as a blow, striking a surface and causing the release of blood from an injury. - **Cast-off pattern:** is formed when blood drops are released from a moving blood-bearing object such as a weapon or an injured person\'s hand. - **Expiration pattern:** An expiration pattern is formed when blood is expelled out of the nose or mouth resulting from an internal injury in the chest or throat, or when a person is suffocated. - **Arterial sputter:** An arterial sputter results from blood being forced out of an artery under high pressure, typically seen in cases of knife or sharp object attack where the weapon has struck a major artery. - **Void pattern:** A void pattern is created when an object blocks the deposition of blood stains on a surface. The blood stains are deposited on the object instead. When the object is removed from the surface, a characteristic pattern can be seen where blood is absent (void) similar to the shape of the object, surrounded by continuously distributed bloodstains. Topic 5\ Death Investigation Autopsy An autopsy is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death; or the exam may be performed to evaluate any disease or injury TYPES OF AUTOPSY - Medico legal autopsy - Pathological autopsy - Virtual autopsy - **Medico legal autopsy**: A medico legal autopsy is conducted only on the request of a legal authority responsible for the investigation of the sudden suspicious and unnatural death - **Pathological autopsy**: Clinical or pathological autopsy is done on death due to natural causes in order to know the exact cause of death - **Virtual autopsy**: Forensic Medicine and Radiology departments of The University of Bern's Institute, has combined the various forms of latest imaginary technologies with forensic science to provide bloodless, minimum invasive method for accidental and homicidal deaths Objectives of Autopsy examination - To find out the exact cause of death, whether natural or unnatural. This includes exact description and recording of all the evidences, injuries and whether death was due to any violence or poisoning etc. - To note down all the injuries, both external and internal including any possible malformations, deformities or disease. - To find out how the injuries occurred and what is the possible weapon of offence. - To find out the exact manner of death, whether suicidal, accidental or homicidal. - To find out the time since death. - To find out the position of the body at the time of death, if possible. - In case of an unknown body, to establish the identity of the person. - Collection of physical evidence at wherever stage necessity arises for the sake of the case and handing over the same to the investigating officer after proper sealing. - To retain relevant viscera and tissues whenever necessity arises and handing over the same to the investigating officer after proper sealing. - In postmortem examination of infants, apart from above mentioned points, it is necessary to establish the viability of the infant and if the infant was live born, then to find out the period of survival and cause of death. [Type of DEATHS] - Natural - Accidental - Homicidal - Suicidal - The most common manner of death is natural death. Natural death is defined as death due to interruption or failure of body functions from ageing or disease. - Accidental death is death following events in which there in no intent to cause harm or death. Road traffic collisions and occupational-related deaths are among the examples that may be considered as accidental deaths. - Homicidal death is death of one person due to another person. There is a motive behind the killing of a person by another. Possible motives are anger, jealousy, cover-up, revenge and others. Slash wound to the neck, multiple stab wounds and manual strangulation. - The act of killing oneself is a suicidal death. There are many ways of taking one's own life, such as hanging, jumping from high places and poisoning. The three most common suicide methods in Malaysia are hanging/ strangulation/ suffocation, jumping from high places and exposure to pesticides. - Natural - Accidental - Homicidal - Suicidal - Rigor mortis or death stiffening or cadaveric rigidity is a state of stiffening of muscles, sometimes also with slight shortening of muscle fibers. During life the muscles are in a slightly contracted state - After passing through the primary relaxation phase or primary flaccidity, soon after death, during which the muscles are totally relaxed, the muscles gradually get stiffened over a period of time, which is known as rigor mortis. - During lifetime, separation of actin and myosin is possible for the extensibility of the muscles. The contraction of the actin and myosin filaments are dependent on the energy provided by ATP (adenosine tri phosphate) and during life a constant supply of ATP is being maintained. Failure of re-synthesis of ATP after death results in the muscle becoming hard and rigid. Some amount of ATP still remains available after death till the glycogen reserve lasts. - Once the glycogen reserve is depleted, there is no more ATP available and the contractile elements are converted into dehydrated, stiff, gel like mass resulting in the muscles themselves becoming hard and rigid. - All the muscles of the body, both voluntary and involuntary are affected. Nysten's rule states that, it does not start simultaneously in all muscles. It first appears in the involuntary muscles; the myocardium becomes rigid in an hour. It becomes noticeable in the eyelids, then the muscles of the face, jaw and neck. - Then it goes downwards to the upper limbs, thorax, abdomen and lower limbs and lastly the fingers and toes. In the individual limbs, it usually progresses from above downwards. It disappears in the same order in which it has appeared. With the passing away of rigor, the muscles once again become softened and this phase is called secondary flaccidity Time chart of Rigor Mortis appearance and disappearance is provided to students also FACTORS AFFECTING RIGOR MORTIS (Chart of this is also provided) ALGOR MORTIS Algor mortis (from Latin algor \'coldness\', and mortis \'of death\'), the third stage of death, is the change in body temperature post mortem, until the ambient temperature is matched. This is generally a steady decline, although if the ambient temperature is above the body temperature (such as in a hot desert), the change in temperature will be positive, as the (relatively) cooler body acclimates to the warmer environment. External factors can have a significant influence. Detail Time chart of algor mortis is provided - The Glaister Equation is solely based on algor mortis. The equation is (98.7 degrees Fahrenheit -- the body temperature) / (1.5). This equation assumes that body temperature drops about 1.5 degrees per hour. - The post-mortem interval would equal the normal body temperature minus the internal temperature of the cadaver when found, and the result will be divided according to the rate of temperature fall per hour (PMI = 37°C -- unknown number of degrees C (temperature of cadaver) ÷ rate of temperature fall per hour) Cadaveric spasm - Cadaveric spasm is a rare form of virtually instantaneous rigor that develops at the time of death with no period of post mortem flaccidity. - Muscles exhibit stiffening at the moment of death. decomposition / Putrefaction - Postmortem decomposition: Also known as Putrefaction - Putrefaction is the post mortem destruction of the soft tissues of the body by the action of bacteria and enzymes (both bacterial and endogenous). - Tissue breakdown resulting from the action of endogenous enzymes alone is known as autolysis. - Putrefaction results in the gradual dissolution of the tissues into gases, liquids and salts. - The main changes which can be recognized in the tissues undergoing putrefaction are changes in color, the evolution of gases, and fluids. Adipocere formation - Saponification or adipocere formation is a modification of putrefaction characterized by the transformation of fatty tissues into a soft, yellowish-white, greasy, (but friable when dry), wax-like substance, with a sweetish odor. - It is first seen over areas of high subcutaneous fat. - It floats on water, and dissolves in alcohol and ether. When heated it melts and then burns with a yellow flame. - Ordinarily it will remain unchanged for years. - The medico-legal importance of adipocere lies not in establishing time of death but rather in its ability to preserve the body to an extent which can aid in personal identification and the recognition of injuries. - The presence of adipocere indicates that the post mortem interval is at least weeks and probably several months. Mummification - Mummification is a modification of putrefaction characterized by the dehydration or desiccation of the tissues. - The body shrivels and skin becomes dry ,leathery and looks blackish brown, clinging to the body frame. - The internal organs also get dried and shriveled up. - As the skin contracts some of the fat cells in subcutaneous tissues are broken and liquid fat smears in the dermis, which becomes translucent. - A mummified body is practically odorless. - The forensic importance of mummification lies primarily in the preservation of tissues which aids in personal identification and the recognition of injuries. - The time required for complete mummification of a body cannot be precisely stated, but in ideal conditions mummification may be well advanced by the end of a few weeks.