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.
What 4 things can blood spatter analysis tell us?
Information that may be gained with bloodstain pattern analysis include, for example, the position of the individual when the blood was deposited (sitting, standing, etc.), the relative position of individuals at the time of bloodshed , the possible type of weapon used as well as possible mechanisms that could have ...
What can be determined from blood spatter?
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.
What is one factor that blood spatter patterns Cannot indicate?
Too much blood can disguise spatter or make stain patterns unrecognizable . Conversely, too little blood, just one or two drops, will likely yield little or no useable information.
Can blood spatter determine velocity?
A Blood spatter analyst may even be able to determine how the victim and assailant moved in the crime scene, if they were rushed, or if they where comfortable etc. 1) Low, medium and high velocity blood spatter: This can help identify the type of weapon that may have been used at a crime scene .
Is blood spatter evidence accurate?
Bloodstain-pattern analysis has been accepted as reliable evidence by appellate courts in one state after another with little or no examination of its scientific accuracy. ... Once one court ruled such testimony admissible, other states’ courts followed suit, often citing their predecessors’ decisions.
Can you tell how old dried blood is?
Non-Destructive Age Testing of Bloodstains
Raman spectroscopy and advanced statistics allow the researchers to date a blood stain accurately, provided said blood stain is less than two years old . Raman spectroscopy involves shining a laser on a sample and measuring the intensity of scattered light.
Are there really blood spatter experts?
Bloodstain pattern analysts , also known as blood spatter experts, collect and analyze physical evidence—specifically, blood. They are specialists in forensic science and crime scene investigation and examine the location and shape of blood drops, stains, puddles, and pools.
What is the difference between blood spatter and splatter?
To spatter means to scatter small particles of a substance. A spatter is the pattern of drops that result from spattering. To splatter means to scatter large particles of a substance. A splatter is the pattern of drops that result from splattering.
Is there such a thing as a blood spatter analyst?
A blood spatter analyst, a type of forensic science expert, investigates crime scenes and reconstructs crimes based on how bloodstains have formed on various surfaces in order to figure out exactly how a crime was committed.
What are 5 conditions that affect the shape of the blood stain?
When blood is impacted, droplets are dispersed through the air. When these droplets strike a surface, the shape of the stain changes depending on the angle of impact, velocity, distance travelled and type of surface impacted .
How do you test for blood spatter?
Further tests at the crime lab can determine if it is human blood or not. The Kastle-Meyer tests uses phenolphthalein and hydrogen peroxide , while HemaStix is a paper strip coated with TMB. This chemical is used to locate traces of blood, even if it has been cleaned or removed.
What shape does a passive drop of blood at a 90 degree angle have?
When a droplet of blood strikes a surface perpendicular (90 degrees) the resulting bloodstain will be circular . Blood that strikes a surface at an angle less than 90 degrees will be elongated or have a tear drop shape.
What is the terminal velocity of a drop of blood in feet second?
Studies conducted by MacDonnell determined the average terminal velocity speed for a falling blood drop of blood to be 25.1 feet /second . This velocity is reached in a maximum falling distance of 20-25 feet. In addition, the size of an individual droplet determines the path of the droplet in free flight.
What is the terminal velocity of a drop of blood?
As a drop falls through the air, it accelerates until it reaches a constant or terminal velocity. Measurements have shown that a blood drop, resulting from dripping at a height of 15 feet, has a volume of about 0.05-ml and falls at a velocity of about 25 feet per second .
What two forces act on a falling drop of blood?
The spherical shape is caused by the surface tension of the blood. Surface Tension causes the blood drop to pull itself in; both horizontally and vertically. The blood drop will settle into a spherical shape, as a result of the surface tension.
