crime scene reconstruction

CRIME SCENE RECONSTRUCTION:BLOODSTAIN PATTERN ANALYSIS

Project Presentation By:Lauren Brown, Ta’Asia Glass & Austin Mutuana

Crime-Scene Reconstruction Defined as the method used to support a likely sequence

of events at a crime scene by the observation and evaluation of physical evidence and statements made by

individuals involved in the incident.

Crime-Scene ReconstructionPrinciples of Crime-Scene Reconstruction

Forensic Scientists work together to reconstruct events that occurred before, during and after the crime.

Law Enforcement secures the crime scene to avoid altered , contaminated or destroyed evidence.

Crime-Scene ReconstructionPrinciples of Crime-Scene ReconstructionPreliminary examination of the crime scene.

Each crime scene has it’s own circumstances.

Physical evidence is a critical factor for crime-scene reconstruction.

Observations are recorded by the following methods: Photographs Notes Sketches

Crime-Scene ReconstructionPrinciples of Crime-Scene Reconstruction

Next, a hypothesis is developed to determine the course of events that took place.

By carefully collecting physical evidence and thoroughly documenting the crime scene, the investigator can unravel the series of events that occurred during the commission of the crime.

Crime-Scene ReconstructionPersonnel Involved in Reconstruction

Law Enforcement Personnel, Medical Examiner and/or a Criminalist work together as a team to answer…

Who? What? When? Where? Why? How?

Crime-Scene ReconstructionPersonnel Involved in Reconstruction

Trained medical examiners can determine whether the body has been moved after death by evaluating the livor distribution throughout the body.

The collection, documentation and interpretation of physical evidence is the foundation of the reconstruction.

Reconstruction develops a likely sequence of events.

Analysis of all data will help create the workable reconstruction model.

Crimes involving violent contact often involve blood stain patterns.

Crime-Scene ReconstructionGeneral Features of Bloodstain Formation

Information uncovered by bloodstain pattern includes: The direction which the blood originated. The angle at which the blood droplet struck a

surface. The location or position of the victim at the time of

wound infliction. The movement of the victim at the scene. The minimum number of blows the victim received. The approximate location of the person delivering

the blows.


Surface Texture is vitally important when interpreting bloodstain patterns. Harder non-porous surfaces such as glass result in less

spatter. Rough surfaces such as concrete result in irregular

shaped spatter possibly a satellite spatter.


Satellite Spatter is small drops of blood distributed around the perimeter of a drop of blood and were produced as a result of

blood impacting the target surface.

The angle of impact is formed between the path of a blood drop and the surface that it contacts.


Impact spatter is the most common type of bloodstain pattern found at a crime scene. Occurs when an object impacts the source of

blood.

Crime-Scene ReconstructionImpact Bloodstain Patterns

Forward spatter travels away from the source in the same direction as the force that caused the spatter.

Back spatter also called blow-back spatter is blood directed toward the source of the force that caused the spatter.

Crime-Scene ReconstructionImpact Bloodstain Patterns

Not all bloodstains appear as spatter patterns, different circumstances often create other type of stains.

Contact/Transfer Patterns occur when an object with blood touches an object that did not have blood on it.

Examples of transfer: Fingerprints Tool prints Handprints Footwear prints Fabric prints in blood

Crime-Scene ReconstructionOther Bloodstain Patterns

Sizes and shapes maybe seen in general transfer, which can result in narrowing down possible tools.

Individualistic features may point to the tool that made the patter.

Simple Transfer Patterns occur when a bloody object makes contact with the surface and isn’t moved afterwards.



Swipe Patterns occur when movement of a bloody object across the surface takes place.

The first transfer patterns will be dark and as it moves it will become lighter and lighter.


Flows-drops are large amount of blood that is pulled by gravity.

Flow may show movement of the object while blood was flowing or after blood has dried .

Different situations can lead to specific patterns which can determine the movement or non-movement of an object or body.


Pools occur when blood is collected in a stable undisturbed level.

Analysts are able to analyze and estimate the drying time of the stains of different sizes.

The important part of pool stains is being able to give a time of the events that led up to the incident.


Even after wiping up the stain, skeletonization remains intact around the edges of the surface .


Drip trail patterns are a series of drops that are separate from the patterns.

Can result from blood dripping off an object or injury. The dripping pattern in normally left by the suspect it can

determine the direction and the speed at which the person was moving.

Crime-Scene ReconstructionDocumenting Bloodstain Pattern Evidence:

Blood spatter patterns of any kind can provide a great deal of information about the series of events that took place at a crime scene.

Investigators should note, study and photograph each pattern and drop, to ensure there is an accurate record of location and to distinguish laboratory samples.

Crime-Scene ReconstructionDocumenting Bloodstain Pattern Evidence: Photographs and sketches should be taken by investigators to

show orientation of the patterns to the scene.

Crime-Scene ReconstructionDocumenting Bloodstain Pattern Evidence: There are two important methods of

documenting bloodstains.

The grid method consists of setting up a dimension over the entire pattern with stakes and string

The perimeter ruler method consists of setting up rectangular borders of rulers around the pattern.

QUESTIONS