Are you a crime junkie? If grisly facts about crimes and criminals just fascinates you, you may be interested to know what reagent may be used at a crime scene to identify blood? While the question seems simple enough, it has a multiple part answer with lots of information, so let’s get started!
Crime scene investigation centers around forensic science, and as you can probably imagine, is extremely tedious and detailed. An investigator or forensic scientist must take a collection of samples including blood evidence left at the scene. If there is no blood evidence where someone died on the scene, investigators or scientists may attempt to shed some light on the subject by using a reagent to test for the presence of blood traces not visible to the naked human eye.
The Luminol Method
Probably the most common type of reagent used at crime scenes to perform these presumptive tests is luminol, with a process called chemiluminescence or luminescence. A presumptive test can be performed by spraying the luminol on the suspected area and blocking out all the light. Any traces of blood in the area sprayed, upon examination will appear as fluorescent blue light photons, now visible to our naked eye.
It all works due to a type of chemical reaction that occurs between the chemicals and the blood. A Luminol solution contains hydrogen peroxide, another of the 3 (total) elements which, when combined together with blood, have the reaction of emitting a blue luminescence. The luminol and the hydrogen peroxide act as the principal agents, and the blood is the catalyst that speeds up and intensifies the reaction during the test.
This presumptive test can reveal the presence of critical blood evidence that investigators or scientists would otherwise miss. The problem is, investigators don’t like to use it very often because it destroys the DNA in the blood samples. This in turn prevents accurate DNA analysis tests.
The Fluorescein Method
As previously mentioned, crime investigators or forensic scientists prefer to use Luminol only as a last resort, primarily due to its destruction of DNA evidence and analysis. Fluorescein is another common chemical and type of presumptive test that can be performed to detect the presence of blood trace evidence left behind.
A solution of brand name Fluorescence is often used at the scene of a crime for detecting blood, and also contains and uses hydrogen peroxide as the other type of primary agent in its chemical reaction with blood. During the test, the reaction time is longer with fluorescein, and it works on footprints too, and in following the trail of a suspect.
With fluorescein, although the test process is also done in darkness, the investigator or scientist must use a type of alternative light source such as LED lighting or fluorescent lighting, as well. And the main big difference is that fluorescein does not contaminate or otherwise destroy DNA evidence or compromise DNA analysis from blood or semen.
The Blue Star Method
Blue Star is yet another example of a similar type of reagent, and is used as one of the presumptive tests used in the identification of blood at crime scenes. It is said to be a higher performance and longer lasting alternative than the others. It boasts the ability to apply it several times and still not compromise the DNA from the blood evidence, and stronger detection of blood on surfaces that have been cleaned with bleach. Peroxide and darkness are the same with this test, so no other light source is necessary.
Forensic serology is a division of forensic science that centers around scientists who deal with samples of bodily fluids that are evidence from crimes. Scientists who work in forensic serology will first make an examination of a sample of something, such as blood cells or semen. Then, they take the same sample of blood cells or semen and work towards identifying it.
Once identified, scientists begin the process of determining DNA identification, with the hopes of an end result of matching it to a suspect. Forensic serology is the branch of forensic science devoted to the detection, identification and classification of bodily fluids in relation to crimes.
Like forensic serology, forensic science focuses on evidence from crimes. Forensic scientists can typically take an active role in traveling to the scene of the crime to collect the evidence themselves, or if preferable, they can occupy a strictly laboratory role and leave the collecting to the CSI investigator. Either way, they are responsible for collecting, analyzing and preserving evidence associated with a crime. This could be analyzing anything from blood or semen, to analyzing financial data!
In both forensic serology and forensic science, the idea is to apply science and the scientific method to solving crimes. Forensic scientists are also known for their expertise, and often called as expert witnesses when criminal cases go to court. They can be called for either the prosecution or the defense.
Crime Scene Cleaners
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