Skip to main content

Forensic Science for Healthcare Professionals

Blood Spatter Analysis

What is Blood Spatter Analysis?

Blood Spatter Analysis or Blood Pattern Analysis (BPA) is the examination of bloodstain shapes, locations, and distribution patterns, to provide an interpretation of the physical events that gave rise to their origin.

blood pattern analysis


In forensic investigations, it is ubiquitous to encounter blood on the crime scene. This blood can be in the form of a pool, dried stains, spatter, expirated blood, etc. Hence, the investigators are required to understand these bloodstains to interpret the events that have occurred on the crime scene, to create a possible hypothesis of the modus operandi, to identify the type of weapon, the direction of the blow, severity of the injury, applicable forces, etc. This whole interpretation is known as Blood Pattern Analysis or Blood Spatter Analysis.


What are the Types of Blood Patterns?

There are many classifications given by blood spatter analyst around the world. I will be using the most common here, to make it understand in a lucid form. 

Passive Blood Pattern: In the form of  flow, pool, saturation, drip/drop, volume.

Projected Blood Pattern: Instrumental, expirated, arterial spurt/gush.

Impact Blood Pattern: Blood splashes, object splashes, drops, drips, trails, object impacts.

Impression Blood Pattern: Transfer, contact, swipe, wipe, secondary



Artifactual Blood Pattern: Voids, fly spots, insect/bug trails, bubbles, blood (dried, skeletonized, separated).

Let me give you hint of some other way to classify and understand this:

Back spatter — blood directed back to the source of energy or force which caused the spatter; often associated with gunshot wounds at the entrance.

Castoff pattern — bloodstain pattern produced when blood is released or thrown in motion from an object carrying blood.

Drip pattern—bloodstain pattern resulting from blood dripping into blood.

Expirated blood—blood propelled from the nose, mouth, or a wound as a result of air pressure and/or air flow  

Impact spatter — bloodstain pattern created when blood receives a blow or force that results in smaller drops being dispersed at random.

Skeleton bloodstain — bloodstain consisting only of an outer periphery after cleaning off the central area when the liquid was partially dry.

Why Blood Pattern Analysis is Needed?

The determinations made from bloodstain patterns at the scene or from the clothing in a case can be used to:

  • Confirm or dismiss assumptions regarding events and their sequence.
  • Determine victim's position. 
  • The evidence of a struggle (standing, sitting, lying). (Blood smears, trails of blood)
  • Confirm or refute statements made in the case: Are there stain patterns consistent with his reported actions on a suspect clothing?
  • Were stain patterns on a victim or in a scene consistent with witness or suspect accounts?


What are Different Velocities Considered in Blood Spatter Analysis?


1. Low Velocity Patterns: These are the patterns where the gravitational pull is up to 5 feet/ second. Such patterns are relatively greater in size.

2. Medium Velocity Patterns: The velocity greater than 5 feet/second and up to 25 feet/second. Preponderant stain size 1 to 4mm.


3. High Velocity Patterns: A velocity of 100 feet/second or greater is considered as high velocity patterns. Preponderant stain size 1mm in size and smaller Mist like appearance.


Determination of Direction of Blood Spatter: 

If a droplet of blood reaches a perpendicular surface (90 degrees) then the resultant bloodstain is circular. That being the stain will be equal in length and width. Blood that hits a surface at an angle of less than 90 degrees will elongate or have the form of a tear drop. Directionality is usually evident as the pointing end of the bloodstain (tail) will always point in travel direction.

90 degree blood stain

direction of blood


Conceptually, the angle of impact is that between the surface and angle line. Blood that reaches a surface at an angle of 90 degrees will be almost round in shape. The pattern will become more elongated and elliptical as the blood impacts at angles decreasing from 90 degrees.


What are the various factors that affects the formation of particular blood spatter?


1. Type of the weapon
2. Force of Impact
3. Site of Injury
4. Position of the victim
5. Angle of Impact
6. Surface of spatter (porous/non porous/ smooth/ rough/ horizontal/ vertical)
7. Amount of blood
8. Climatic Conditions
9. Drying time
10. Clotting time, etc.

How to determine the point of origin of blood spatter ?

The specific element, on a two-dimensional surface, can be traced back to the directionality of several bloodstains. Upon deciding the directionality of a group of stains, it is possible to determine a two-dimensional point or region for the stain group.








Conclusion: The blood pattern analysis is a wide field in the science of investigation. It requires a great expertise in the court of law. As a career, it is one of the best option for the aspiring forensic experts. Often the blood pattern analyst are called in court to explain the cause of spatter, modus operandi, possible type of weapon, and to draw the chain of events.




Comments

  1. Extremely useful information which you have shared here about Background Check Service for Business...... This is a great way to enhance knowledge for us, and also beneficial for us. Thank you for sharing an article like this.

    ReplyDelete
  2. Thanks for publishing such great information. You are doing such a great job. This information is very helpful for everyone. Keep it up. Thanks. thesis proofreading

    ReplyDelete
  3. Extremely useful information which you have shared here about...... This is a great way to enhance knowledge for us, and also beneficial for us. Thank you for sharing an article like this. Cyber Forensic Service in london

    ReplyDelete
  4. For unsupervised urine drug tests, you would do just fine, for the most part. However, if you’re going to be supervised on your urine drug test, you want to be cautious, especially when it comes to transporting and dispensing your pee. You might want to hide your synthetic urine kit in a secret leg strap or stash undies when muggling it in. Then, use something like a prosthetic penis, or the urine belt kit, to dispense it discreetly. More on that later. Just use the test panel when you have a strong urge to pee since it must be used right away Visit: https://www.urineworld.com/

    ReplyDelete
  5. I found decent information in your article. I am impressed with how nicely you described this subject, It is a gainful article for us. Thanks for share it. Cyber Security Latest News Canada

    ReplyDelete

Post a Comment

Popular posts from this blog

Crime Scene Search Methods

The Crime Scene is search for the physical evidences (visible or invisible). There are various types of search methods employed by the investigating officers and the forensic scientists at the scene of crime. The searching methods mainly depends on: Type of Crime (Rape, murder, burglary, theft, etc.) Nature of Crime (Homicide, suicide, or accident) Size of the crime scene (macroscopic or microscopic) Location of the crime scene (indoor, outdoor, combination of indoor or outdoor, or any remote area like underwater, desert, etc.) Complexity of the crime scene  Before deciding the search method, all the investigators and the forensic experts must follow the general guidelines (check list) to observe the crime scene after due recording: 1. Are the doors and windows locked or unlocked? Open or shut?  2. Are there signs of forced entry, such as tool marks or broken locks? 3. Is the house or the crime scene is in good order? If not, do

Introduction to Forensic Ballistics

By Dr. Bhoopesh Kumar Sharma Forensic Expert & Associate Professor Introduction to Ballistics: The term ballistics refers to the science of study of the action, motion and  behaviour  of a projectile during its flight in any given medium. The flight path of a bullet includes:  • Travel down the barrel  (Internal Ballistics), • Path through the air  (External Ballistics),  and  • Path through a target  (Terminal Ballistics) Forensic Ballistics: Is that branch of forensic science which deals with the examination of the firearm and related evidences encountered at the scene of crime in a shooting incident, and their linkage to the firearm, and Identification of the shooter. A ballistic expert need to answer the following questions: 1. Type of The Firearms used 2. Identification of the Firearm 3. Individual Characteristics of Firearm 4. Range of Firing 5. Direction of Firing 6. Identification of the Shooter 7. Medico legal aspects: - Suic