Bloodstain pattern analysis (BPA) is the interpretation of bloodstains at a crime scene in order to recreate the actions that caused the bloodshed. Analysts examine
the size, shape, distribution and location of the bloodstains
to form opinions about what did or did not happen.
What is the importance of studying the bloodstain pattern?
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 can blood spatter tell an investigator?
Based on the varying sizes and shapes of the blood drops, investigators can often tell
what type of weapon caused the spatter
, determine the general area where the attack occurred, and track the positions of the victim. … “Oftentimes blood spatter analysis is used to test an alibi, such as self-defense,” Johnson says.
What are the 4 types of passive bloodstains?
- Passive Bloodstain. Passive Bloodstain on a rough surface (such as wood or concrete)
- Projected Bloodstain. Projected Bloodstain, possibly a Cast-Off Pattern or a HVIS.
- Transfer Bloodstain.
What is the original drop of blood that casts or gives off a satellite called?
Parent Drop
– A drop of blood from which a wave, cast-off or satellite spatter originates.
What type of evidence is blood typing?
Blood typing is
class evidence
because many people share the same blood type and this evidence is used to exclude a person as a suspect.
What type of evidence is blood spatter?
-Blood spatter- Droplets and patterns can reveal key evidence such as the
type of weapon that was used in the crime
, the time of the crime, and other details. Blood spatter analysts can determine the general manner of the crime using the area of origin, the angle of impact, and satellite droplets.
Who analyzes blood evidence?
Forensic scientists who analyze bloodstain evidence are typically called
bloodstain pattern analysts
. It is best if the bloodstain pattern analyst is present at the crime scene to begin the investigation, but it is possible to use photographs, video, and reports from a crime scene investigator for the analysis.
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.
What are the 3 categories of bloodstains?
Bloodstains are classified into three basic types:
passive stains, transfer stains and projected or impact stains
. Passive stains include drops, flows and pools, and typically result from gravity acting on an injured body.
What is wipe pattern?
A wipe pattern is “
An altered bloodstain pattern resulting from an object moving through a pre-existing wet bloodstain
.”
What are the six types of blood spatter patterns?
- 1902, Dr. John Glaister described 6 patterns: a. …
- circular drops. b. arterial gusheswalls or ceilings produced by.
- pumping action of the heart. c. splashesshaped like exclamation points;аused to.
- d. smearsleft when victim or suspect touches surface. e. …
- smears. f. poolsperson remains in one place bleeding heavily.
What is the absence of stains in an otherwise continuous bloodstain pattern called?
Void
. an absence of stains in an otherwise continuous blood pattern, like a reverse shadow. Wipe Pattern. a bloodstain pattern created when an object moves through an existing stain, removing it or changing its appearance.
What Cannot be determined by blood spatter?
Which of the following CANNOT be determined by observing blood spatter?
The DNA of the victim
. The position of the assailant at the time of the spatter.
What are the 4 types of evidence?
The four types of evidence recognized by the courts include
demonstrative, real, testimonial and documentary
.
What are the two major types of evidence?
There are two types of evidence; namely,
direct evidence and circumstantial evidence
.
