How it works: This test uses two specialized antibodies to detect the presence of human Glycophorin A which is found in red blood cell membranes. The antibodies are applied to the suspected sample by using a strip test assay.
How do forensic scientists test blood?
The most publicized test by crime shows is the Luminol process in which a chemical is sprayed onto a surface where blood is suspected to be. The chemical reacts with traces of blood, producing a chemi-luminescence, or apparent glow, as a result of the chemical reaction that occurs.
How is blood evidence tested?
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.
How is blood detected at a crime scene?
Crime scene investigators use luminol to find traces of blood, even if someone has cleaned or removed it. The investigator sprays a solution of luminol and the oxidant. The iron in blood catalyses the luminescence.
How is blood spatter used in forensics?
The general role of the Bloodstain Pattern Analyst in a criminal investigation is to assist in the reconstruction of those events of an alleged incident that could have created the stains and stain patterns present at a crime scene, on items of physical evidence recovered from that scene and on items of clothing that …
What are the three confirmatory test for blood?
Confirmatory tests for blood include identification of blood cells under a microscope [Shaler, 2002], crystal tests such as the Teichman and Takayama tests [Shaler, 2002; Spalding, 2003], and ultraviolet absorption tests [Gaensslen, 1983].
Can forensics tell how old 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.
Is blood evidence Class evidence?
Class evidence consists of substances such as blood and hair, which can be used to place an individual in a general class but cannot be used to identify an individual. For example, blood typing can be used to establish whether someone has A, B, AB, or O blood, but cannot point to a person.
Is blood biological evidence?
Blood is one of the most important biological traces that are often found on the crime scene. Due to valuable information it contains, it is considered to be a very important forensic tool. … Such crucial information can point criminal investigation in the right direction and help solve the crime.
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.
Does Luminol only show blood?
If luminol reveals apparent blood traces, investigators will photograph or videotape the crime scene to record the pattern. Typically, luminol only shows investigators that there might be blood in an area, since other substances, including household bleach, can also cause the luminol to glow.
Can too much luminol destroy DNA?
Luminol has been widely used in the field of crime scene investigations to detect latent blood; however, luminol has the tendency to destroy DNA evidence. … DNA was extracted from blood-containing denim substrates after fluorescein was applied to the substrates.
Which test reacts with blood stains and turns pink if blood is present?
Phenolphthalein is a presumptive test that reacts with the heme molecule present in blood. A positive reaction gives a pink color.
What are the 3 types of blood stains?
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.
Is blood spatter physical evidence?
This form of physical evidence requires the analyst to recognize and interpret patterns to determine how those patterns were created. Bloodstain pattern analysis (BPA) is the interpretation of bloodstains at a crime scene in order to recreate the actions that caused the bloodshed.
Is blood spatter analyst real?
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.