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. ... – Transfer Stains/Patterns -A transfer bloodstain pattern is created when a wet, bloody surface contacts a surface that is not bloody .
How is evidence transferred?
Transfer evidence is defined as any evidential substance or particle such as blood , fluids , hairs, fibers , paint, and skin that is exchanged between an assailant and the victim or the scene of the crime . ... This transfer often occurs when forcible contact occurs between persons, vehicles, or objects.
How is blood stored evidence?
Liquid blood evidence is generally collected from blood pools but can be collected off of clothing as well, using a gauze pad or a sterile cotton cloth. Once the sample is collected it must be refrigerated or frozen and brought to the laboratory as quickly as possible.
How should evidence with blood on it be packaged and stored?
Whole blood should be stored in a refrigerator . Always package tubes of blood separately from any other evidence items in a crushproof container. Evidence that is wet or that may contain body fluids (blood, semen, etc.) must be air-dried completely.
How is blood evidence used in forensic science?
The use of blood in forensic analysis is a method for identifying individuals suspected of committing some kinds of crimes . ... When scientists identify blood types, they rely on slight differences in the antigens, or protein markers on the surfaces of red blood cells in a blood sample.
Is blood considered physical evidence?
Blood and other body fluid stains may be encountered as physical evidence in a variety of crimes such as homicide, vehicular hit-and-run, and burglary.
What can degrade a biological sample collected as evidence?
Improperly used, bleach could destroy biological evidence. There will be occasions when it is not possible to collect a stain by cutting it from an object (e.g. stain is on a concrete floor). ... It may be useful to test the “unstained” area with an appropriate presumptive test to see if it contains a biological sample.
What types of fragile evidence must be collected first?
Collecting prints at the crime scene should be every investigator’s top priority. Fingerprints from the suspect as well as elimination fingerprints from the victim will also be needed for comparison (the same holds true for palm and bare footprints).
Which type of evidence should never be packaged in plastic containers?
There’s a simple rule of thumb for deciding which type of evidence packaging—wet evidence goes in paper containers (wet evidence can degrade if placed inside plastic containers) and dry evidence goes in plastic. Items that could be cross-contaminated must be packaged separately.
What type of evidence is blood splatters?
Using blood-spatter pattern evidence, it is possible to determine the area of origin of the blood , the direction the blood was traveling, and the angle of impact when the blood struck an object. The type of weapon used to cause an injury is indicated by the size of the blood droplets found in the blood spatter.
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.
How is dried blood collected?
Dried blood spot specimens are collected by applying a few drops of blood, drawn by lancet from the finger, heel or toe, onto specially manufactured absorbent filter paper . The blood is allowed to thoroughly saturate the paper and is air dried for several hours.
What are 4 types of evidence?
The four types of evidence recognized by the courts include demonstrative, real, testimonial and documentary .
What is the strongest type of evidence?
The most powerful type of evidence, direct evidence requires no inference. The evidence alone is the proof.
What are the 7 types of evidence?
- Personal Experience. To use an event that happened in your life to explain or support a claim.
- Statistics/Research/Known Facts. To use accurate data to support your claim.
- Allusions. ...
- Examples. ...
- Authority. ...
- Analogy. ...
- Hypothetical Situations.
