Introduction
New to SIRCHIE's line of Blood Search Reagents! The BLUESTAR Forensic Kit affords the crime scene investigator a complete tool to determine the presence or absence of blood. The extreme sensitivity of BLUESTAR allows the detection of bloodstains down to 1:10,000 dilutions, including minute traces that have been visibly washed off, with or without detergent. (Tub with blood stains)
Unlike other blood reagents, total darkness is not always required. Subsequent DNA Profiling and ABO Typing is possible because BLUESTAR does not alter the DNA in suspect blood stains.
Reaction-False Positives
When reacting with blood, the BLUESTAR® FORENSIC latent bloodstain reagent emits an intense blue-white chemiluminescence in the range of 420 to 440 nanometers. Keep in mind, however, that "false" positives may occur due to the presence of many common household detergents, chlorine (from bleach), certain paints and varnishes, copper (from plumbing), certain iron-metabolizing plants like lichens, thyme and some tree mosses, and certain soils rich in iron.
Such "false" reactions are easily identifiable by the trained technician because their color, brightness, and duration of chemiluminescence differs from those of the typical reaction from blood. Typically, "false" reactions offer markedly dimmer chemiluminescence and are whiter in color. "False" reactions due to chlorinated detergents are often worth a second look, because they may reveal attempts to wash or clean up bloodstains, and to conceal crimes of violence.
Photography
Photography of latent blood prints developed and visualized from chemiluminescence is not fundamentally different from regular daylight photography. The same basic elements of photography apply: subject lighting, ISO setting, aperture setting, and shutter speed) interact in exactly the same way. Photography of BLUESTAR® FORENSIC detected blood prints is easy and produces excellent results.
Equipment
The chemiluminescence produced by the reaction of the BLUESTAR® FORENSIC latent bloodstain reagent to blood is bright enough that, most often, no special equipment is needed. However, relatively long exposures may be needed for maximum photo quality and a tripod and flexible cable release are highly recommended in order to maintain stability of the camera, which must remain motionless during the time of the exposure. A wide-angle lens is recommended.
Use at the Crime Scene
BLUESTAR offers different kits so by all means follow the specific recommendations supplied with the kit you will be using. Shelf-life of BLUESTAR after mixing is limited to a maximum of 24 hours. When mixing the tablets in the carrier solution, do not shake or invert the sprayer. Rather… swirl the sprayer until the tablets are dissolved. (Blood Print on Tile ===>)
Safety Precautions
As with handling any chemical, use Best Practices during the application of the spray. Wear latex gloves, safety glasses or goggles, dust respirator and protective clothing.
Final Word
Chemical field tests are considered “Presumptive” in determining the nature of the substance tested. None of the bloodstain reagents explained in this, or preceding articles in this series of “BloodTips” offer definitive proof that the tested substance is blood. The final determination must be made in the crime laboratory. Best practices and agency protocol dictate that samples of the substance tested are to be collected for scrutiny in the lab.
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