........WORKBOOK I, PART II
CRIME SCENE RECONSTRUCTION FUNDAMENTALS
Workbook I, Part II, CRIME SCENE RECONSTRUCTION FUNDAMENTALS, provides the Detective-trainee with all requisite knowledge required to properly reconstruct a crime scene to determine events at the fundamental level.
1. Reconstruction
- Reconstruction is based on the results of crime scene examination, laboratory analysis, and other independent sources of information to reconstruct case events. Reconstruction often involves the use of inductive and deductive logic, statistical data, information from the crime scene, pattern analysis, and laboratory analysis results on a variety of physical evidence. Reconstruction can be a very complex task, linking many types of physical evidence, stain pattern information, analytical results, investigative information, and other documentary and testimonial evidence into a complete entity. Reconstructions are often desirable in criminal cases in which eyewitness evidence is absent or unreliable. They are important in many other types of cases, too, such as automobile and airplane accidents, fire and arson investigation, and major disasters.
2. Stages in reconstruction
- Reconstruction is considered a scientific fact-gathering process. Reconstruction generally involves a group of actions that will set the stage for crime reconstruction. The following are the five separate stages commonly used in the process
of reconstruction:
- 1 -Data collection: all information or documentation information obtained at the crime scene, from the victim, or witnesses. Data including condition of the evidence, obvious patterns and impressions, condition of the victim, etc., are reviewed, organized, and studied.
- 2 -Conjecture: before any detailed analysis of the evidence is obtained, a possible explanation or conjecture of the events involved in a criminal act may be done, but it must not become the only explanation being considered at this stage. It is only a possibility. There may be several more possible explanations, too.
- 3 -Hypothesis formulation: further accumulation of data is based on the examination of the physical evidence and the continuing investigation. Scene examination and inspection of the physical evidence must be done. Scene and evidence examination includes interpretation of bloodstain and impression patterns, gunshot patterns, fingerprint evidence, and analysis of trace evidence. This process leads to the formulation of an educated guess as to the probable course of events, a hypothesis.
- 4 -Testing: once a hypothesis is formulated, further testing must be done to confirm or disprove the overall interpretation or specific aspects of the hypothesis. This stage includes comparisons of samples collected at the scene with known standards and alibi samples, chemical, microscopical and other analyses and testing. Controlled testing or experimentation of possible physical activity must be done to collaborate the reconstruction hypothesis.
- 5 -Theory formation: additional information may be acquired during the investigation about the condition of the victim or suspect, the activities of the individuals involved, accuracy of witness accounts, and other information about the circumstances surrounding the events. All the verifiable investigative information, physical evidence analysis and interpretation, and experimental results must be considered in testing and attempting to verify the hypothesis. When it has been thoroughly tested and verified by analysis, it can be considered a plausible theory.
3. Pattern analysis in reconstruction
- Pattern evidence is one type of physical evidence encountered at a majority of crime scenes. Often, forensic scientists do not take this type of evidence seriously enough, and think of it as not being very scientific. Pattern evidence at crime scenes is, however, extremely valuable in the reconstruction of crimes and the activity that has taken place at the crime scene. It can be used to prove or disprove a suspect's alibi or a witness's version of what took place at the crime scene, to associate or dissociate the involvement of persons or objects in particular events, or to provide the investigators with new leads or information for further investigation. Pattern evidence is generally created by the contact of two surfaces (persons, vehicles, or objects) that results in the formation of impressions, imprints or markings. These impressions may be from static or stationary contact or dynamic or moving contact and may be two-dimensional or three-dimensional. In some cases, the contact may be a transfer of material from one surface to another resulting in pattern evidence in the form of a stain or deposit. Pattern evidence also results from the fracture, breaking or cutting of an object.
The following is a list of pattern evidence commonly found at different crime
scenes:
- 1 Bloodstain patterns
2 Glass fracture patterns
3 Fire burn patterns
4 Furniture position patterns
5 Track-trail patterns
6 Tire or skid mark patterns
7 Clothing article damage or position patterns
8 Modus operandi and crime scene profile patterns
9 Projectile trajectory and powder residue patterns
10 Injury or wound patterns
Pattern evidence found at crime scenes should be carefully documented, processed, enhanced, or collected.
The techniques used for pattern evidence reconstruction are the same as those examinations of other types of physical evidence: Recognition, Identification, Individualization, Interpretation, and Reconstruction.
4 Bloodstain pattern analysis
- Bloodstain pattern analysis has been defined in several ways. Bloodstain pattern analysis seeks to define the facts surrounding an investigation by the use of the physical nature of bloodstains. It is the evaluation of the static aftermath of bloodshed in an attempt to determine the actions that created the bloodstains found at the crime scene. Oftentimes, the bloodstain patterns provide a window to the past. The totality of these definitions is that the size, shape, and distribution patterns of the bloodstains found at a crime scene where bloodshed has occurred can be used to reconstruct the bloodshed event(s). The bloodstain pattern analysis is in some cases more useful and significant than the serological or DNA information obtained from the blood.
The bloodstain patterns reveal not who but what with regard to the circumstances of bloodshed. The what of bloodshed is the result of careful examination and study of the bloodstains appearance at the crime scene.
The following are some examples of how reconstruction can be made by the study of the bloodstain evidence:
- Direction of travel of the blood droplets.
Distance of blood source to target surface.
Angle of impact of blood droplet.
Type of blood droplets.
Determination of blood trails, their direction, and the relative speed of motion.
Nature of the force used to create the bloodshed.
-Nature of the object used to cause bloodshed, the number of blows involved, and
relative location of persons/objects near bloodshed.
Sequencing of multiple events associated with the bloodshed.
Interpretation of contact or transfer patterns.
Estimation of elapsed time and volume of bloodshed
5. Glass fracture patterns
- Broken glass at crime scenes can sometimes aid in reconstruction, providing information about the events which took place, and assisting in proving or disproving an alibi or witness's story. Glass fracture patterns are most often associated with burglary, criminal mischief, shooting incidents, and fire scenes.
The most common types of information that can be obtained by studying glass fracture patterns are:
- Direction of impact force applied (from inside out or outside in).
Approximate force of impact.
Approximate angle of impact of force.
Determination of the type of glass fracture.
Determination of the sequence of firing, direction of firing, and the type of firearm for the projectile holes present.
Estimation of the fire temperatures, direction of fire travel, and the intensity of heat from the melted glass.
The use of glass fracture patterns in crime scene reconstruction relies on careful recognition, documentation, and study of radial and concentric glass fracture markings. Other information for reconstruction is obtained by analysis of rib marks, spatial relationships, crack marks, and the condition of any melted glass. To conduct even a basic reconstruction based on glass fracture evidence, investigators should be familiar with the different categories of glass and generally how each type of glass fractures. Glass is an amorphous, super-cooled liquid, composed primarily of silicon dioxide (sand). There are three general classes of glass: plate, tempered, and safety.
Each type of class has certain characteristics, and will fracture differently.
Plate glass is a common variety of glass used to make windows and mirrors. When plate glass is exposed to a force significant enough to rupture the surface tension and break the glass, characteristic pie-shaped glass shards are formed. If broken glass remains in the frame the observed fracture pattern will consist of a center point, where the force contacted the windowpane, with radiating (radial) fracture lines going out from the center point. In addition, there will be fracture lines running perpendicular to the radial lines, concentric fracture lines. By carefully examining a broken edge of a piece of glass along a radial line, you can determine the direction of force. This analysis is helpful in determining from which side of the glass the window was broken. Investigators can use this information to confirm a false burglary report by showing that the window was broken from the inside out rather than outside in as reported by the homeowner.
Safety glass is found in automobile windshields. Basically, safety glass is two separate panes of plate glass adhered together with a clear laminated layer. While this glass fractures in a similar way to plate glass it remains intact after breaking due to the laminate layer. Safety glass was designed to reduce injuries to passengers should they be propelled into the windshield as the result of a traffic accident. Caution must be exercised when interpreting safety glass fracture patterns in that there are two separate panes of glass, which will have independent radial and concentric fractures. Since safety glass remains intact it can provide valuable information in shooting incidents. The direction of each gunshot can be determined by locating the crater, which
is located on the side of glass facing the impacting force. Also, if more than one bullet penetrates the windshield it is possible to sequence the shots if the bullet holes are close enough together that their separate radial fracture lines converge. The subsequent bullet hole can be determined because radial lines from that bullet hole terminate where they meet the existing radial line from the prior fracture.
Tempered glass is a single pane glass that is durable and difficult to fracture due to its significant surface tension. When enough force is applied to break this surface tension the entire pane of glass fractures into thousands of small pieces, commonly referred to as dicing. Tempered glass is used in side windows of automobiles. In most cases a vast majority of the diced glass falls from
the window frame, into the car and on the ground.
6. Fire burn patterns
- Fire burn patterns often provide information on the various factors which led to or caused a fire. Detailed study of the burn patterns generally helps in determining the point of fire origin, the direction of fire travel, and the degree of damage of a fire, which may contain clues for arson investigations.
The following is a partial list of common patterns found at fire scenes:
- Inverted cone or V pattern
Multiple points of origin burn patterns
Low burn pattern configurations
Depth of charring patterns or alligator patterns
Trailer patterns
Smoke stain pattern, Melted material patterns
Concrete spalling patterns
Every fire forms a pattern that is determined chiefly by the configuration of the environment, the availability of combustible material, and the type and intensity of the fire. From a study of the fire patterns and a determination of any deviations from normal or expected patterns, an experienced fire investigator can reconstruct a fire scene.
7. Furniture position patterns
- At an indoor crime scene, the position and condition of furniture often yields information about the events that caused the pattern, their sequence, and possible actions of perpetrators and victims. Displaced or broken furniture can indicate that a struggle took place. Patterns of disarray in ordinary or expected furniture placement or condition may further reveal actions taken by suspects or witnesses.
8. Track-trail patterns
- Occasionally, track-trail patterns are encountered at crime scenes. Proper interpretation of them can yield information about how many persons were present at a scene, whether they were moving about, the nature of the movement (walking, running) and the direction of travel, and whether heavy objects were being carried or dragged. Some of these types of patterns can give class characteristic information or data about the individual responsible for producing the patterns, such as shoe size, stride length, sex, weight, or any abnormalities in movement or gait.
9. Tire and skid mark patterns
- Tire or skid mark patterns are often seen at outdoor crime scenes, and can provide important reconstruction information for the crime scene investigator. The value of skid mark patterns in traffic accident reconstructions is well known and documented. However, the use of these patterns in crime scene investigation and reconstruction is often neglected. These markings can yield information about the number and types of vehicles involved, the possible speed of travel, direction of travel, whether or not brakes were applied, and whether turns were made.
10. Clothing or article patterns
- This type of pattern evidence can be subtle or, at times, very obvious! Detailed observation, measurement, documentation, and correct interpretation of these patterns can be valuable and essential in crime scene reconstruction. Some examples of the types of information that can be obtained from these patterns are whether a suspect ransacked a scene, proof or disproof of an alibi, direction and route taken by a suspect, physical contact between persons, persons and vehicles, or between vehicles, disturbances of expected patterns at the crime scene, and possible information about the sequence of events.
11. Modus Operandi and scene profile patterns.
- These patterns are more subtle, and require careful observation, as well as extensive knowledge of criminals and details of their previous crimes. Modus operandi (MO) patterns can link apparently unrelated crimes together at the investigative stage. These patterns include information such as methods used to gain entry to a premises, types of weapons preferred, types of force used, types of language used, the sequence of actions followed by the suspect, types of property taken, and the types of any materials left behind at the scene. Scene profiles often reveal information with regards to identification of primary v. secondary scenes; active scenes v. passive scenes; organized scenes v. disorganized scenes.
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[center][lspdlogo=250][/lspdlogo][color=transparent]........[/color][/center]
[center][b][color=#004040][size=120]WORKBOOK I, PART II[/size][/color][/center][/b]
[center][color=#004040][size=100]CRIME SCENE RECONSTRUCTION FUNDAMENTALS [/size][/color][/center]
Workbook I, Part II, CRIME SCENE RECONSTRUCTION FUNDAMENTALS, provides the Detective-trainee with all requisite knowledge required to properly reconstruct a crime scene to determine events at the fundamental level.
[b]1. Reconstruction[/b]
[list=none]
Reconstruction is based on the results of crime scene examination, laboratory analysis, and other independent sources of information to reconstruct case events. Reconstruction often involves the use of inductive and deductive logic, statistical data, information from the crime scene, pattern analysis, and laboratory analysis results on a variety of physical evidence. Reconstruction can be a very complex task, linking many types of physical evidence, stain pattern information, analytical results, investigative information, and other documentary and testimonial evidence into a complete entity. Reconstructions are often desirable in criminal cases in which eyewitness evidence is absent or unreliable. They are important in many other types of cases, too, such as automobile and airplane accidents, fire and arson investigation, and major disasters.
[/list]
[b]2. Stages in reconstruction[/b]
[list=none]
Reconstruction is considered a scientific fact-gathering process. Reconstruction generally involves a group of actions that will set the stage for crime reconstruction. The following are the five separate stages commonly used in the process
of reconstruction:
[list]
[*]1 -Data collection: all information or documentation information obtained at the crime scene, from the victim, or witnesses. Data including condition of the evidence, obvious patterns and impressions, condition of the victim, etc., are reviewed, organized, and studied.
[*]2 -Conjecture: before any detailed analysis of the evidence is obtained, a possible explanation or conjecture of the events involved in a criminal act may be done, but it must not become the only explanation being considered at this stage. It is only a possibility. There may be several more possible explanations, too.
[*]3 -Hypothesis formulation: further accumulation of data is based on the examination of the physical evidence and the continuing investigation. Scene examination and inspection of the physical evidence must be done. Scene and evidence examination includes interpretation of bloodstain and impression patterns, gunshot patterns, fingerprint evidence, and analysis of trace evidence. This process leads to the formulation of an educated guess as to the probable course of events, a hypothesis.
[*]4 -Testing: once a hypothesis is formulated, further testing must be done to confirm or disprove the overall interpretation or specific aspects of the hypothesis. This stage includes comparisons of samples collected at the scene with known standards and alibi samples, chemical, microscopical and other analyses and testing. Controlled testing or experimentation of possible physical activity must be done to collaborate the reconstruction hypothesis.
[*]5 -Theory formation: additional information may be acquired during the investigation about the condition of the victim or suspect, the activities of the individuals involved, accuracy of witness accounts, and other information about the circumstances surrounding the events. All the verifiable investigative information, physical evidence analysis and interpretation, and experimental results must be considered in testing and attempting to verify the hypothesis. When it has been thoroughly tested and verified by analysis, it can be considered a plausible theory.
[/list][/list]
[b]3. Pattern analysis in reconstruction[/b]
[list=none]
Pattern evidence is one type of physical evidence encountered at a majority of crime scenes. Often, forensic scientists do not take this type of evidence seriously enough, and think of it as not being very scientific. Pattern evidence at crime scenes is, however, extremely valuable in the reconstruction of crimes and the activity that has taken place at the crime scene. It can be used to prove or disprove a suspect's alibi or a witness's version of what took place at the crime scene, to associate or dissociate the involvement of persons or objects in particular events, or to provide the investigators with new leads or information for further investigation. Pattern evidence is generally created by the contact of two surfaces (persons, vehicles, or objects) that results in the formation of impressions, imprints or markings. These impressions may be from static or stationary contact or dynamic or moving contact and may be two-dimensional or three-dimensional. In some cases, the contact may be a transfer of material from one surface to another resulting in pattern evidence in the form of a stain or deposit. Pattern evidence also results from the fracture, breaking or cutting of an object.
The following is a list of pattern evidence commonly found at different crime
scenes:
[list]1 Bloodstain patterns
2 Glass fracture patterns
3 Fire burn patterns
4 Furniture position patterns
5 Track-trail patterns
6 Tire or skid mark patterns
7 Clothing article damage or position patterns
8 Modus operandi and crime scene profile patterns
9 Projectile trajectory and powder residue patterns
10 Injury or wound patterns[/list]
Pattern evidence found at crime scenes should be carefully documented, processed, enhanced, or collected.
The techniques used for pattern evidence reconstruction are the same as those examinations of other types of physical evidence: Recognition, Identification, Individualization, Interpretation, and Reconstruction.
[/list]
[b]4 Bloodstain pattern analysis[/b]
[list=none]
Bloodstain pattern analysis has been defined in several ways. Bloodstain pattern analysis seeks to define the facts surrounding an investigation by the use of the physical nature of bloodstains. It is the evaluation of the static aftermath of bloodshed in an attempt to determine the actions that created the bloodstains found at the crime scene. Oftentimes, the bloodstain patterns provide a window to the past. The totality of these definitions is that the size, shape, and distribution patterns of the bloodstains found at a crime scene where bloodshed has occurred can be used to reconstruct the bloodshed event(s). The bloodstain pattern analysis is in some cases more useful and significant than the serological or DNA information obtained from the blood.
The bloodstain patterns reveal not who but what with regard to the circumstances of bloodshed. The what of bloodshed is the result of careful examination and study of the bloodstains appearance at the crime scene.
The following are some examples of how reconstruction can be made by the study of the bloodstain evidence:
[list]
Direction of travel of the blood droplets.
Distance of blood source to target surface.
Angle of impact of blood droplet.
Type of blood droplets.
Determination of blood trails, their direction, and the relative speed of motion.
Nature of the force used to create the bloodshed.
-Nature of the object used to cause bloodshed, the number of blows involved, and
relative location of persons/objects near bloodshed.
Sequencing of multiple events associated with the bloodshed.
Interpretation of contact or transfer patterns.
Estimation of elapsed time and volume of bloodshed[/list]
[/list]
[b]5. Glass fracture patterns[/b]
[list=none]
Broken glass at crime scenes can sometimes aid in reconstruction, providing information about the events which took place, and assisting in proving or disproving an alibi or witness's story. Glass fracture patterns are most often associated with burglary, criminal mischief, shooting incidents, and fire scenes.
The most common types of information that can be obtained by studying glass fracture patterns are:
[list]Direction of impact force applied (from inside out or outside in).
Approximate force of impact.
Approximate angle of impact of force.
Determination of the type of glass fracture.
Determination of the sequence of firing, direction of firing, and the type of firearm for the projectile holes present.
Estimation of the fire temperatures, direction of fire travel, and the intensity of heat from the melted glass.
[/list]
The use of glass fracture patterns in crime scene reconstruction relies on careful recognition, documentation, and study of radial and concentric glass fracture markings. Other information for reconstruction is obtained by analysis of rib marks, spatial relationships, crack marks, and the condition of any melted glass. To conduct even a basic reconstruction based on glass fracture evidence, investigators should be familiar with the different categories of glass and generally how each type of glass fractures. Glass is an amorphous, super-cooled liquid, composed primarily of silicon dioxide (sand). There are three general classes of glass: plate, tempered, and safety.
Each type of class has certain characteristics, and will fracture differently.
Plate glass is a common variety of glass used to make windows and mirrors. When plate glass is exposed to a force significant enough to rupture the surface tension and break the glass, characteristic pie-shaped glass shards are formed. If broken glass remains in the frame the observed fracture pattern will consist of a center point, where the force contacted the windowpane, with radiating (radial) fracture lines going out from the center point. In addition, there will be fracture lines running perpendicular to the radial lines, concentric fracture lines. By carefully examining a broken edge of a piece of glass along a radial line, you can determine the direction of force. This analysis is helpful in determining from which side of the glass the window was broken. Investigators can use this information to confirm a false burglary report by showing that the window was broken from the inside out rather than outside in as reported by the homeowner.
Safety glass is found in automobile windshields. Basically, safety glass is two separate panes of plate glass adhered together with a clear laminated layer. While this glass fractures in a similar way to plate glass it remains intact after breaking due to the laminate layer. Safety glass was designed to reduce injuries to passengers should they be propelled into the windshield as the result of a traffic accident. Caution must be exercised when interpreting safety glass fracture patterns in that there are two separate panes of glass, which will have independent radial and concentric fractures. Since safety glass remains intact it can provide valuable information in shooting incidents. The direction of each gunshot can be determined by locating the crater, which
is located on the side of glass facing the impacting force. Also, if more than one bullet penetrates the windshield it is possible to sequence the shots if the bullet holes are close enough together that their separate radial fracture lines converge. The subsequent bullet hole can be determined because radial lines from that bullet hole terminate where they meet the existing radial line from the prior fracture.
Tempered glass is a single pane glass that is durable and difficult to fracture due to its significant surface tension. When enough force is applied to break this surface tension the entire pane of glass fractures into thousands of small pieces, commonly referred to as dicing. Tempered glass is used in side windows of automobiles. In most cases a vast majority of the diced glass falls from
the window frame, into the car and on the ground.
[/list]
[b]6. Fire burn patterns[/b]
[list=none]
Fire burn patterns often provide information on the various factors which led to or caused a fire. Detailed study of the burn patterns generally helps in determining the point of fire origin, the direction of fire travel, and the degree of damage of a fire, which may contain clues for arson investigations.
The following is a partial list of common patterns found at fire scenes:
[list]Inverted cone or V pattern
Multiple points of origin burn patterns
Low burn pattern configurations
Depth of charring patterns or alligator patterns
Trailer patterns
Smoke stain pattern, Melted material patterns
Concrete spalling patterns[/list]
Every fire forms a pattern that is determined chiefly by the configuration of the environment, the availability of combustible material, and the type and intensity of the fire. From a study of the fire patterns and a determination of any deviations from normal or expected patterns, an experienced fire investigator can reconstruct a fire scene.
[/list]
[b]7. Furniture position patterns[/b]
[list=none]
At an indoor crime scene, the position and condition of furniture often yields information about the events that caused the pattern, their sequence, and possible actions of perpetrators and victims. Displaced or broken furniture can indicate that a struggle took place. Patterns of disarray in ordinary or expected furniture placement or condition may further reveal actions taken by suspects or witnesses.
[/list]
[b]8. Track-trail patterns[/b]
[list=none]
Occasionally, track-trail patterns are encountered at crime scenes. Proper interpretation of them can yield information about how many persons were present at a scene, whether they were moving about, the nature of the movement (walking, running) and the direction of travel, and whether heavy objects were being carried or dragged. Some of these types of patterns can give class characteristic information or data about the individual responsible for producing the patterns, such as shoe size, stride length, sex, weight, or any abnormalities in movement or gait.
[/list]
[b]9. Tire and skid mark patterns[/b]
[list=none]
Tire or skid mark patterns are often seen at outdoor crime scenes, and can provide important reconstruction information for the crime scene investigator. The value of skid mark patterns in traffic accident reconstructions is well known and documented. However, the use of these patterns in crime scene investigation and reconstruction is often neglected. These markings can yield information about the number and types of vehicles involved, the possible speed of travel, direction of travel, whether or not brakes were applied, and whether turns were made.
[/list]
[b]10. Clothing or article patterns[/b]
[list=none]
This type of pattern evidence can be subtle or, at times, very obvious! Detailed observation, measurement, documentation, and correct interpretation of these patterns can be valuable and essential in crime scene reconstruction. Some examples of the types of information that can be obtained from these patterns are whether a suspect ransacked a scene, proof or disproof of an alibi, direction and route taken by a suspect, physical contact between persons, persons and vehicles, or between vehicles, disturbances of expected patterns at the crime scene, and possible information about the sequence of events.
[/list]
[b]11. Modus Operandi and scene profile patterns.[/b]
[list=none]
These patterns are more subtle, and require careful observation, as well as extensive knowledge of criminals and details of their previous crimes. Modus operandi (MO) patterns can link apparently unrelated crimes together at the investigative stage. These patterns include information such as methods used to gain entry to a premises, types of weapons preferred, types of force used, types of language used, the sequence of actions followed by the suspect, types of property taken, and the types of any materials left behind at the scene. Scene profiles often reveal information with regards to identification of primary v. secondary scenes; active scenes v. passive scenes; organized scenes v. disorganized scenes.
[/list]
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