Through analysis of blood splatter, an investigator can tell how the person was killed and from what angle it was done. It can also tell whether the act done fast or as slowly as possible. Blood splatter can greatly help in crime investigation through the analysis of it.
How can blood spatter analysis be useful in an investigation?
Bloodstain pattern analysis provides important forensic information about the crime under investigation; it tells what happened. Bloodstain patterns occur in several distinct categories, each revealing a piece of the crime scene puzzle.
What does blood spatter size tells the investigator?
By measuring the width and length of the stain, the angle of impact can be calculated, helping investigators determine the actions that may have taken place at the scene.
What information can we figure out using blood spatter?
The blood spatter pattern can tell a trained investigator much about what crime may have been committed and rule out other types of crime. Together with other evidence, blood spatter can be very useful in piecing together what took place, identifying the victim, and determining who was responsible.
What is the forensic value of blood spatter?
To help reconstruct events that caused bloodshed, analysts use the direction and angle of the spatter to establish the areas of convergence (the starting point of the bloodshed) and origin (the estimation of where the victim and suspect were in relation to each other when bloodshed occurred).
What four properties of a crime scene can be identified from blood spatter?
proper Bloodstain Pattern Analysis:Distance from the blood source to the target.Direction of travel and impact angles.Nature of the force used to cause the bloodshed.The object used to cause the bloodshed.Sequencing of multiple bloodshed events.Interpretation of contact or transfer patterns.
What can blood tell you at a crime scene?
These droplets of blood have been acted on by forces other than gravity, either being cast off of a weapon, or spraying from a victim onto a surface. The shape and size of these droplets can help to determine the positioning of a victim, the type of weapon used, and the force used in the crime.
How reliable is blood spatter analysis?
The validity of bloodstain pattern analysis has been questioned since the 1990s, and more recent studies cast significant doubt on its accuracy.
How important is blood spatter analysis in crime scene reconstruction?
Pattern evidence is also key in reconstruction. Blood Spatter is an important indicator at a crime scene because it usually tells an investigator what type of weapon caused the injury. High-Velocity blood spatter typically results from a gun shot wound.
What happens to the size of the blood spatter as velocity increases?
As the level of force or velocity increases, the number of blood drops put in flight and the distance they travel away from the blood source increases. The diameter of the drops decreases as force increases, with many of the blood drops being 1 mm in diameter.
What information can blood drop diameter provide to the forensic scientist at a crime scene?
When investigating bloodstain patterns at the scene of the crime, forensic investigators can therefore measure the diameters of bloodstains to determine whether the bleeding individual was standing, being held away from the ground, or was closer to the ground.
What information can an investigator gain from locating the area of origin of a bloodstain?
What information can an investigator gain from the location of the area of origin of a bloodstain pattern? Position of the person form which the pattern originated.
What does an analyst have to measure to determine the angle of blood spatter?
Then, he or she uses a protractor on the level line in the area where the strings converge to determine the angle of flight for each spatter. If the spatters are mostly on a wall, the analyst can measure the distance from the area of convergence to the wall to find out where the victim was located.
Understanding Blood Spatter as Evidence
If you turn your television on in the evening it is very likely you will find a television show where investigators are using some type of forensic or scientific method to collect or identify evidence.
There are three basic types of blood patterns
This occurs with a minimal amount or no force. The blood pattern is much larger than those of medium velocity and high velocity.
What is BPA in crime scene?
Known as BPA, blood pattern analysis invaluable tool for any crime-scene investigator, as although (as we saw in Mini Mile #9) although you can semi-successfully clean-up a crime-scene, you can’t tamper with the laws of physics. So by understanding at what speed, height, distance and angle the blood travels, and how it impacts with a surface, that can help an investigator to establish what crime took place, the sequence of events, the position of those involved, and to confirm or deny an eye-witness’s, victim’s and perpetrator’s description of the events.
What is arterial spray?
Sometimes called arterial spray, this is caused by pressurised blood discharging from a tear or rupture of one of the body’s main arteries (carotid, radial, femoral, brachial, temporal and the aorta, although spray from the aorta is less likely, owing to its position in the chest cavity).
How many blood patterns are there?
There are eight primary blood patterns. #1 A Single Drop: A single drop of blood, falling vertically and forming an evenly spread spherical shape shows that the victim was standing and motionless at the time they bled, with the blood stain being more tear-drop shaped, the greater the victim moves.
What happens when blood droplets are propelled through the air?
When a victim is violently struck, the force of the blow results in the expulsion of blood droplets from the injury, at speed, from a height and at an angle, but as the blood droplets are propelled through the air, they will disperse into even smaller droplets and become more scattered the further they are propelled from a single point of impact.
Why is blood spatter analysis important?
Blood spatter analysis is a very useful forensic aid in crime investigations for murders and other violent crimes. This is not exactly a modern brainwave, but the age-old idea has been reinforced massively by modern research. Advances in biology, especially genetics, have helped this science become much more reliable.
How does blood spatter reveal the identity of a killer?
Analysis of blood spatter can reveal the killer’s identity in several ways: through DNA, through any diseases he might be carrying, or through deduction using the physics of how blood would behave when subjected to the motions in a crime.
What is the name of the blood that drips from a pool?
Passive Spatter: Blood that drips because of gravity and as just an aftereffect of the violence is called the passive spatter. This can range from isolated drops of blood to stagnated pools. Projectile Spatter: As the name suggests, blood that drops as a result of an external impulse is called projectile spatter.
What chemical is used to detect blood?
Luminol and Fluorescein are the main chemical indicators used to spot blood. Both of these cause blood to glow (the latter under a special light and when viewed with the corresponding eyewear), making it easier to spot. This helps differentiate passive, projectile, and contact spatters.
Why is liquid blood used for DNA testing?
This is especially helpful when there are multiple victims. It reveals any abnormalities with the blood, which can show if either the victim or the criminal were suffering from any diseases.
What is the purpose of lab analysis?
Lab analysis can determine if the blood is indeed human. It provides DNA evidence. Liquid blood is soaked, and dried up blood has to be swabbed for this crucial test.
What is contact spatter?
Contact Spatter: This includes marks which have been left as imprints of something drenched in blood coming in contact with a target area.
Why do investigators use blood stain patterns?
Besides testing, investigators use blood stain patterns to help determine if a crime was committed. There are different types of blood stain patterns that an investigator looks for, these patterns are as follows: – Drip Stains/Patterns – blood stain patterns that are created due to the force of gravity acting on liquid blood.
What does it mean when you find blood on a knife?
Blood found on the blade of a knife could mean that a crime was committed and someone was stabbed- but it could also mean that the victim sliced their own finger.
Why is blood evidence important?
This is because an investigator must initially determine if a crime has been committed. It’s important to determine if a crime has been committed because the presence of blood does not necessarily mean ...
Where is blood evidence collected?
Blood evidence isn’t just collected off of weapons, but can also be collected off of the floor or other surfaces in a crime scene. This blood is also tested to determine if the blood came from the victim or the suspect. Besides testing, investigators use blood stain patterns to help determine if a crime was committed.
Why is it important to determine if a crime has been committed?
It’s important to determine if a crime has been committed because the presence of blood does not necessarily mean that there ever was a crime. This determination has to be made in a case where a person is reported missing since it will help investigators. The blood found can then be tested and see if it belongs to the victim;
