Crime Scene Training

BloodTips-03 Luminol Reagent

By: Don Penven

Luminol is a chemiluminescent substance that is used as a presumptive test for the presence of blood. Making use of the peroxidase-like activity of the heme portion of hemoglobin, Luminol produces a bluish-white light that can be viewed in total darkness. Invisible blood stains react with the Luminol reagent by luminescing—but darkness is essential. Luminol is a useful test for searching large areas for blood, especially if the area has been cleaned up. Sensitivity:1:100,000.

 

Luminol is available in several different packages and quantities. It is supplied as a pre-measured dry powder along with a specific amount of distilled water. Once mixed, Luminol has a relatively short shelf life.

The advantages of using Luminol for locating minute traces of blood are numerous: it is non-destructive to subsequent DNA profiling; it is a relatively safe compound if used according to directions; and it is simple to mix and apply.

 

Preparations for use:

Note: Since the luminescence fades rather quickly, have a tripod-mounted camera ready to use as soon as luminescence appears.

Warning! Luminol, in its solid or mixed state, is hazardous and should be mixed in a well-ventilated area or laboratory hood. Severe skin, eye and respiratory irritant—wear protective clothing, gloves and safety glasses/goggles.

1. Remove cap from bottle of “B” solution.

2. Remove clip and pour entire contents of pouch “A” powder into bottle of “B” solution.

3. Recap bottle with supplied spray head attachment and shake well until all solid material dissolves.

4. Luminol is ready to be applied to suspect areas. Set the spray nozzle to “MIST.”

Instructions for use:

1. Photograph the scene prior to processing with Luminol.

2. Turn off all lights and darken the area as much as possible—luminescence may be very weak and is best seen in total darkness. Note: A night vision flashlight (red beam) such as LVL100 LumaVision™ may be used to illuminate the area while processing the scene.

3. Process small 2-3 sq. ft. areas at a time. When luminescence is revealed, prepare to take photos  (absolutely no flash is to be used). Notes: Photo Evidence Markers such as PEN15 can be used to indicate the locations of luminescence so they can later be photographed under full light or with a flash.

4. Reapply Luminol as necessary if luminescence fades too quickly before photos can be taken.

 

 Carpet suspected of holding blood prints

 

 

 

 

 

 

 

 

 Luminol developed footprint

 

 

 

For complete instructions, you may download the Technical Information Bulletin on Luminol 

 

BloodTips-02 Dischaps Reagents

By: Don Penven

Note: Dischaps is the name of a product line manufactured by Sirchie Finger Print Laboratories. It refers to the type of packaging for a series of different chemical reagents. This packaging refers to DISsposable CHemical Applicators.

 

DISCHAPS™ packaging virtually eliminates the possibility of contamination of chemical reagents, and it dramatically increases shelf life. Reagents are contained within easily crushed glass ampoules. The ampoules are then sealed inside tough, flexible polyethylene dispenser tubes.

Blood DISCHAPS™ applications rely on using the contact method of testing—that is, a few drops of ethyl alcohol or distilled water (See Technical Information Bulletin) are placed on a strip of filter paper, and the wet filter paper is pressed against the suspected stain. The DISCHAPS™ reagent is then applied to the filter paper, thus preserving the original evidence stain.

 

PHENOLPHTHALEIN DISCHAPS™ (DCB100)

Note:  Phenolphthalein reagent requires that ethyl alcohol be used to wet the filter paper during the contact stain lifting method.

Blood causes a Pink stain in just a few seconds. This reagent is considered by many field crime scene technicians to be one of the most reliable presumptive tests for the presence of blood because of its non-reaction to plant materials. Sensitivity=1:500,000.

 

Phenolphthalein reagent reaction to blood 

 

 

LEUCO-MALACHITE DISCHAPS™ (DCB200)

An intense Blue/Green color reaction in 3 seconds is presumptive evidence that

blood is present. Sensitivity (1:10,000).

 

Leuco-malachite Reaction

 

 

LUMINOL DISCHAPS™ (DCB300)

 Luminol reagent requires a darkened area for observation. This is the ideal reagent for

“aged” or invisible blood stains. In fact, the older the stain, the brighter the Blue/

White color reaction (within five seconds). Sensitivity: 1:100,000.

 

Luminol Reaction

 

 

For more specific instructions for use of the Dischaps Blood Test Reagents, you may download the Technical Information Bulletin  <===

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BloodTips-01 Introduction to On-Scene Identification of Blood

By: Don Penven

The purpose of BloodTips is to provide quick tutorials in the use of the most frequently used blood screening methods at crime scenes. These tests are PRESUMPTIVE in nature. They, like narcotic and drug field tests, serve a singular purpose—they provide the crime scene investigator with the knowledge that a particular stain possesses the possibility that it is blood, and these tests are not a substitute for crime laboratory analysis.

The most commonly employed field tests available for use at crime scenes are:

1. Phenolphthalein
2. Leuco malachite
3. Luminol

A variety of commercially-available packaging methods permit simplified, uncomplicated use of these reagents at crime scenes. Each BloodTips post will present a simplified application procedure while existing posts on this blog provide more in-depth coverage of these techniques.

Uses are strongly advised the conduct their own experiments using each of these processes prior to any use at a crime scene. The crime scene investigator is also encouraged to examine the Material Safety Data Sheets (MSDS) readily available from the manufacturer to learn of any hazards that may exist when using these reagents:

To download these MSDSs, please use the following links:

Phenolphthalein:  http://www.sirchie.com/Assets/msds/dcb100a.pdf,  http://www.sirchie.com/Assets/msds/dcb100b.pdf

Leuco malachite:  http://www.sirchie.com/Assets/msds/dcb200a.pdf, http://www.sirchie.com/Assets/msds/dcb200b.pdf

Luminol: http://www.sirchie.com/Assets/msds/dcb300.pdf

The Contact Method of Testing

In order to preserve the integrity of the stain to be testing, we strongly recommend that the Contact method of stain sampling be used in all cases.

Procedure:

• Using a clean piece of filter paper, moisten it by adding a few drops of ethyl alcohol or distilled water, whichever is indicated on the instructions accompanying the particular reagent.
• Press the wet filter paper against the suspected stain for a few seconds.
• Please the filter paper test strip on a clean surface (paper towel, napkin, etc.)
• Add the test reagent to the stain.

In the case of phenolphthalein a pink stain will develop in a few seconds indicating the presumptive presence of blood.

In the case of leuco malachite an intense blue/green stain will develop in a few seconds indication the presumptive presence of blood.

In the case of luminol, the presumptive presence of blood will be indicated to a bluish-white luminescence.  This luminescence is only visible in near total darkness.

 

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