Practical Crime Scene Processing and Investigation PDF

Practical Crime Scene Processing and Investigation Chapter 15 – The Body as a Crime Scene Learning Objectives  Describe the basic types of port mortem changes that occur after death.  Explain the relationship between the ME and the crime scene investigator, as it...

Practical Crime Scene Processing and Investigation Chapter 15 – The Body as a Crime Scene Learning Objectives  Describe the basic types of port mortem changes that occur after death.  Explain the relationship between the ME and the crime scene investigator, as it relates to authority over the body.  Describe the activities involved in conducting a detailed examination of the body in-situ Learning Objectives  Describe the role of the crime scene investigator at the morgue.  Understand basic mechanisms of injury. The Body as a Crime  Alive or dead, the body of the victim represents a significant scene that must be fully documented and processed.  The body should be considered as a “scene” and processed appropriately.  The approach to the body is really no different than the approach to any crime scene. Examination of a corpse in situ  The corpse is approached in much the same fashion as any crime scene.  It must be : – Assessed – Observed – Documented – Searched – Collected – Analyzed  These actions are inserted into normal crime scene methodology as appropriate, but have to be considered specifically to the corpse. Assessment  A critical aspect of assessment involves verifying death.  This is accomplished is based on two general observations: – Evident trauma inconsistent with life – Absence of normal life signs Assessment  Evident trauma inconsistent with life may include: – Major head trauma (clear disruption of the brain) – Decapitation – Massive blood loss – Presence of decomposition  The presence of any one of these conditions can be taken as presumptive evidence of death. Assessment  Absence of normal life signs which include: – Lack of a pulse in major arteries (carotid, femoral) – Lack of a heartbeat – Lack of respiration – Lack of evident body heat – Lack of constriction of the pupils in response to light – Lack of flushing in the nail beds – Lack of movement or response to stimuli  The presence of any combination of these conditions is not taken as presumptive evidence of death and may warrant life- saving  If all these conditions are absent, death is highly probable. Observations  Once initial assessment is complete and death is confirmed by some means, the technician should make note of specific observations relating to the body.  Position, injuries, clothing and associated evidence should be noted.  An important additional consideration are the post mortem changes which include: – Livor mortis – Rigor mortis – Algor mortis – Decomposition – Insect activity Livor Mortis  Livor Mortis is caused by settling of the blood (as a result of gravity) in the small vessels of the circulatory system.  It manifests itself as a red – purple discoloration of the skin.  It may appear in as little as 30 minutes following death and generally becomes fixed within 8 hours of death.  Once “fixed” a change of body position will not result in alteration of the livor mortis patterns. Livor Mortis  To determine if the livor mortis is fixed, the crime scene technician presses a gloved finger to an area of the discoloration. If the area blanches (becomes lighter) the livor is not fixed.  Livor mortis patterns may help the investigation: – In recognizing subsequent manipulation of the body after death (e.g., when the pattern is inconsistent with final position) – It may assist the Medical Examiner in determining the post mortem interval (time since death). Rigor Mortis  Rivor Mortis is caused by a chemical reaction in the muscles as they break down after death.  It manifests itself as a stiffening of the muscle. – This stiffening occurs in all muscles, but manifests itself first in smaller muscles (e.g., jaw and face). – It takes longer to become evident in large muscles groups (e.g., appendages, torso)  Rigor appears within 2 hours of death, becoming greatest at 8-12 hours after death. It will disappear within 24-48 hours after death. Rigor Mortis  Many factors affect the onset and departure of rigor mortis.  As with mivor mortis, rigor assists in two main ways: – In recognizing subsequent manipulation of the body after death (e.g., when the body stiffens and is then moved to some alternate position) – It may assist the Medical Examiner in determining the post mortem interval (time since death). Algor Mortis  Algor Mortis is a loss of body heat in the corpse.  It is best determined by taking a core body temperature (e.g., insertion of thermometer probe into the liver), but can be estimated based on external temperature readings.  Body temperature is highly variable, important factors include: – Ambient environmental conditions – Body habitus (e.g., thin or fat) Algor Mortis  Due to the variability, estimates based on body temperature should always be left to the Medical Examiner.  The primary value of algor mortis is in estimating the the post mortem interval (time since death). Decomposition  Decomposition of the corpse can cause any number of possible conditions depending upon the circumstances of the scene.  These include: – Normal putrefaction of tissue where the body breaks down naturally as a result of bacteria – Adiopecere where the tissue becomes wax like. – Mummification where the tissue dries out and mummifies.  The most common aspect is the normal decomposition. Decomposition  Normal putrefaction of the tissue occurs as a result of bacteria within the gastor0intestinal tract of the body.  Putrefaction typically manifests itself in the abdomen as: – Swelling of tissues – Black or blue discoloration of tissue – Protrusion of the eyes or tongue – Ultimately resulting in slippage of skin and purging of fluids. Decomposition  Putrefaction of the tissue is highly variable.  Major factors include environmental conditions, including temperature and humidity.  Putrefaction may aid the Medical Examiner in estimating the post mortem interval. Insect Activity  Entomological (insect) activity will begin in and around the body very quickly after death.  The various insects involved in this activity have defined life cycles, which if properly noted may assist in defining the post mortem interval.  The primary insects of interest include: – Blow flies – Beetles – Wasps Fly Activity  Flies will begin laying eggs on an exposed corpse within 20 minutes of death.  They lay the eggs in and around moist openings: – Nostrils – Corner of the eyes – Mouth – Open injuries – Any other opening that is exposed  The eggs hatch and become larva (maggots), creating a maggot mass. Fly Activity  The maggots upon reaching maturity abandon the body and enter the soil or surrounding areas.  There they become pupae (a small hard brown casing).  Flies will ultimately emerge from the pupae and begin the life cycle all over.  By observing and collecting the various stages of flies present on the body and in the scene, an entomologist may be able to estimate the post mortem interval. Authority Over the Body  Once observations are complete the body must be manipulated, examined and collected in and of itself.  A major concern for the crime scene technician is authority over the body. In most jurisdictions, the corner or medical examiner has absolute authority for the body.  Before moving, significantly manipulating or collecting artifacts from the body, coordination must be effected. ME and Investigator Relationship  If no ME Investigator is on scene, the crime scene investigator has an absolute responsibility to: – Respect the ME’s authority and not alter the body without permission – Capture appropriate scene context and share that with the ME, to assist them in establishing the manner and cause of death.  The crime scene investigator acts as the ME’s eyes and ears in all instances.  Detailed Examination of the Body on Scene  Detailed examination of the body entails: – In-depth notes of body position, clothing, wounds and associated evidence. – Detailed photographs of all aspects of the body, both in-situ and once rolled over. – A search for fragile and other evidence, including examination with both white light and the ALS. – Collection of the body without significantly altering physical evidence (e.g. dragging the body through existing blood pools)  Detailed Examination of the Body on Scene  Detailed examination of the body entails: – Examination of the hands for evidence (e.g., DNA, gunshot residues, bloodstains) – If allowed by the ME, collection of clothing considered important (e.g., bloodstained items) to prevent the loss of this evidence when the body is placed in the body bag. – Examination of the areas beneath the body, that were not exposed during early on-scene efforts.  Detailed Examination of the Body at the Morgue  Examination of the body by the crime scene investigator continues at the morgue.  The morgue offers: – Better lighting and environmental conditions. – Better position of the body for examination (e.g., on the examination table versus some odd position in the scene)  Examination of a Live Body  The live victim represents several issues: – They must be examined in detail and any evidence or injuries documented and collected. – Gender concerns may cause sensitivity issues.  A medical professional or SANE Nurse are the best approach.  Live individuals are encountered as a function of: – Attempted murders – Rapes and sexual assaults – Apprehended suspects  Mechanisms of Injury  The crime scene technician is not specifically responsible for identifying the types of wounds found on a victim, but their recognition of basic wounds has value. – Recognition can help direct investigative resources (e.g., looking for a knife versus a gun) – Allow them to communicate more effectively with the Medical Examiner – Aid them in describing wounds while on scene.  Mechanisms of Injury  The general mechanism of injury that are of specific observational concern to the crime scene technician include: – Asphyxial injuries – Sharp force trauma – Blunt force trauma – Gunshot trauma  Other mechanisms are important, but less so to the scene technician from an observation and description aspect.  Asphyxia Mechanisms of Injury  Asphyxia occurs when the body is unable to take in oxygen and or eliminate carbon dioxide.  There are various forms including – Strangulation – Smothering – Choking – Drowning – Positional or mechanical asphyxia – Chemical asphyxia  Asphyxia Mechanisms of Injury  Strangulation causes hypoxia, a lack of sufficient oxygenated blood entering the brain  Rarely is the actual airway occluded.  Findings may include: – Congestion of the facial features – Abrasions or contusions of the neck – Hemorrhage of the neck muscles – Ligature below the Adam’s Apple in garroting cases – Ligature above the Adam’s Apple in hanging cases  Asphyxia Mechanisms of Injury  Choking cases will have little physical indicators other than the foreign object that caused the choking.  Drowning causes cerebral anoxia, where water enters the lungs and prevents any oxygen from entering the brain through the circulatory system  Positional or mechanical asphyxia creates a condition where normal breathing is not possible as a result of position or compression and hypoxia results.  Sharp Force Mechanisms of Injury  Sharp force involves physical cutting of the skin and tissue.  The two typical forms of sharp force are: – Stab – a wound which is deeper than it is long. – Incised wound – a wound which is longer than it is deep.  Primary mechanism of death is exsanguination (loss of blood).  Sharp Force Mechanisms of Injury  Wounds may be gaping or narrow.  They will typically have a clean margin (cut versus torn).  External bleeding may not be evident  There may be associated bruising and or marks caused by forceful insertion of the weapon.  The ME may be able to define general orientation of the weapon to the wound (e.g., locating a sharp versus blunt side of the blade). Incised Wound Stab Wound  Blunt Force Mechanisms of Injury  Blunt force involves crushing and tearing of the skin and tissue.  The primary forms of blunt force are: – Contusions (bruising) – blood escapes into surrounding tissue resulting in discoloration. – Abrasions – minor damage to the outer layers of skin. – Lacerations - a physical tear of the tissue, creating an irregular margin wound with tissue bridging. Laceration  Blunt Force Mechanisms of Injury  External lacerations and blunt force generally are not the cause of death.  Typically there are associated blunt force injuries to internal organs and or the brain.  Gunshot Mechanisms of Injury  Firearm injuries result when bullets and or fragments of bullets penetrate, perforate or graze the body.  Gunshot wounds are classified as – Penetrating – bullet enters but does not exiot. – Perforating – bullet enters and exit. – Grazing – bullet skims across the external aspects of the tissue but does not enter the body – Tangential – bullet skims across the body producing a series of shallow wounds that penetrate to the subcutaneous tissue.  Gunshot Mechanisms of Injury  Gunshot wounds are also classified based on the distance between the muzzle and target. Classifications include: – Contact – the muzzle of the weapon is pressed against the body resulting in soot and gasses entering the wound. – Close Contact – the weapon is close enough for heat effects to occur to the skin. Stippling (powder driven into the skin) manifests itself around the wound. – Intermediate – the weapon is far enough away that heat and soot effects are eliminated and only stippling appears. – Indeterminate – no heat, soot or stippling is noted, suggesting either a distance shot or an intermediate object was between the weapon and the wound.  Gunshot Entry Versus Exit  Gunshot entry wounds tend to be: – Symmetrical (circular or elliptical) – Surrounded by an abrasion ring – Depending upon muzzle to target distance may exhibit soot and stippling (partially burned powder driven into the skin)  Gunshot exit wounds tend to be: – Asymmetrical and irregular – Lack soot and stippling – Exception is the “shored” exit wound. Produced when the exit is against an object or the skin around the exit is supported by additional tight clothing (e.g. a belt or bra strap) May appear similar to the entry wound Entry Gunshot Wound Exit Gunshot Wound