Crime Scene Training

Blood Spatter Training From U of WA

The University of Western Australia offers a comprehensive program in Forensics. Using special permission, we are pleased to provide links to some of their outstanding training material on “Blood Spatter.”

What is Forensic Science: This document offers a good perspective overview of a topic of interest to all CSIs.  What Is Forensic Science

All About Blood: Blood is a fluid that makes up approximately eight percent of the total weight of humans. This equates to between four and five litres in females and between five and six litres in males.  All About Blood

Properties of Blood: Learn about blood viscosity, surface tension, density, blood droplets and more…  Properties of Blood

Latent Blood Prints – Methods For Chemical Enhancement

Blood is often found on various surfaces at crime scenes where physical violence occurred. Therefore, blood acts as a transfer medium for latent fingerprints and shoeprints. On some occasions the blood residue retains enough color and detail to permit direct photographic recovery, but generally the blood marks are too faint to permit photography using conventional light sources.

In a report published by the California Department of Justice, Bureau of Forensic Services. scientists conducted significant research indicating that certain reagents may be introduced to the visible stains or areas suspected of containing latent blood impressions.

For many years, forensic scientists have used reagents such as Leucomalachite or Ninhydrin to develop blood stains, but both of these substances have a tendency to run off or distort the prints on non-porous surfaces. On the other hand, Amido Black has proven to be quite useful.

 This article reviews three popular methods for blood print enhancement: Amido Black, Leuco Crystal Violet (LCV) and Hungarian Red

Amido Black

Amido black is very sensitive and works well on non-porous surfaces but its high background color (light to medium blue) compromises contrast on multi-colored porous surfaces.

 Amido Black is a protein stain, and as such should not be considered as even a presumptive test for blood, let alone a confirmatory test. The protein may be present in other body fluids, in addition to blood. However, other actual presumptive tests may be successful after the application of amido black.

The Amido Black staining solution can be methanol—or water-based. Amido Black in methanol has a greater staining power, but due to the toxicity of the methanol, it is also more dangerous. For use on a crime scene (for example, shoeprints in blood) the water-based staining solution is advised.

 Amido Black Aqueous Solutions—Field or Lab Use

To Create an Aqueous Fixing Solution—Solution No. 1 (makes 1000ml):

1. Weigh out 20g of 5-Sulphosalicylic Acid. Place in a clean, dry, 2 liter glass beaker.

2. Measure out 1-liter of Distilled Water. Add to the 5-Sulphosalicylic Acid while stirring with a magnetic stirrer.

A clear water-based Fixing Solution will be produced

3. Transfer the water-based Fixing Solution to a clean, dry, labeled, 1 liter plastic coated glass bottle equipped with a tightly fitting screw cap. (Unused water-based Fixing Solution will keep indefinitely.)

To Create An Aqueous Working Solution—Solution No. 2 (makes 1000ml):

1. Weigh out 2g of Amido Black. Place in a clean, dry, 2 liter glass beaker.

2. Weigh out 20g of citric acid. Add to the Amido Black.

3. Measure out 1 liter of distilled water. Add to the beaker. Stir with a magnetic stirrer for at least 30 minutes. A blue-black working solution will be produced.

4. Transfer the water-based Working Solution to a clean, dry, labeled 1 liter plastic coated, glass bottle with a tightly fitting screw cap. (Unused water-based Working Solution will keep indefinitely.)

Amido Black  Application Procedure:

Aqueous Solutions

Note: The fixing and working solutions may be applied using a spray application. For tray development follow the procedure below:

 Photographs of any visible prints must be taken before proceeding. Important Note : Before using this technique on a corpse, clear the procedure with the Coroner’s or Medical Examiner’s Office.

1. Pour sufficient water-based fixing solution to treat the article into a clean, dry, metal dish or pan.

2. Immerse the article in the fixing solution for five to six minutes. Longer times may be needed to fix heavy blood deposits. Beware of cross-contamination of DNA evidence if more than one article is processed. Discard the water-based fixing solution.

3. Pour sufficient water-based working solution into a clean, dry, metal dish or pan to treat the article. Pour a similar volume of distilled water into two other containers. If the article cannot be fully immersed, apply the working solution and distilled water using a wash bottle above the prints, and allow the solutions to run down over the prints.

4. Immerse the article in the working solution for three to four minutes. Working solution may be replenished as needed. Discard used working solution when complete.

5. Immerse the article in distilled water. Rock the dish gently until excess dye has been removed from the background and greatest contrast is achieved between the prints and the background.

6. Allow the article to dry at room temperature.

7. Photograph useful prints.

Staining can be cleaned using a solution of 10% bleach.

You may download a copy of the complete Amido Black Technical Bulletin Here:

 

 

 

Amido Black Latent Print

Leuco Crystal Violet

This reagent does not react to the normal finger constituents found in latent fingerprints like eccrine or sebaceous deposits. Rather, this reagent has an affinity for heme-based materials. When LCV and hydrogen peroxide come into contact with the hemoglobin in blood, a catalytic reaction occurs and a blue to purple/violet reaction product occurs. Leuco Crystal Violet may be used on both porous and non-porous surfaces, and may be applied with a fine mist spray or by immersing an object in the solution.

A number of sources offer LCV in kit-form, with pre-packaged and pre-measured reagents. To download the complete technical Information Bulletin: Click This Link To Technical Information

 

 

 LCV Shoeprint on tile floor

  Hungarian Red

Hungarian Red was developed through a cooperative effort of the police forces in Hungary and Holland. The intent was to create a formula that would be highly sensitive to blood residue, and subsequent testing has indicated that Hungarian Red may be more sensitive than other processes such as Amido Black.

Hungarian Red is an aqueous solution for staining impressions found in blood. It is much safer than other staining compounds due to its water-based formula. It has been used in actual crime scenes to recover nearly invisible latent fingerprints and footprints in blood. NOTE: As with similar chemicals, collect all DNA evidence from the crime scene before using Hungarian Red because this process will interfere with subsequent blood analysis. Do not use Hungarian Red on handwriting samples, inks, hairs, fibers, and other physiological fluids that will be subsequently subjected to other forms of forensic examination.

 Hungarian Red may be used on most porous and non-porous surfaces.

Lifted traces and weak traces on dark or confusing backgrounds fluoresce under a green alternate

light source (520nm-560nm) such as the, MMX100 megaMAXX™ and MMX300 megaMAXX™ III. Once fluoresced, view and photograph the evidence with orange or red barrier filters.

 PROCEDURE

Hungarian Red is supplied in sprayer containers. Place small objects in a suitable tray and spray the reagent onto the object from a distance of 6"-9" (15.2cm-22.9cm). Allow about one minute for the dye

to set. Then, wash lightly with water or a water/acetic acid mixture. Remove any remaining water

droplets with compressed air or a hair dryer set on low heat. The surface must be completely dry before attempting to lift the developed prints using gelatin-type lifters. When examining larger objects, apply the reagent directly to the surface.

 You may download a complete copy of the Technical Information Bulletin

 

 

The left side of this image shows visible red staining from Hungarian Red. It fluoresces when excited with 520-560nm (right).

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How Police Find Latent Blood Prints

Latent fingerprints, as described in earlier articles in this series, are fingerprints left at a crime scene that are not readily visible to the naked eye. But some crime scenes, especially those where physical violence has occurred, may harbor latent blood fingerprints and foot prints as well.

Identifying Stains

The first step is to determine if the visible stains are probably blood. The tests most often employed by CSIs are either Phenolphthalein or Leucomalachite. Keep in mind, however, that some reagents will interfere with subsequent blood typing or DNA analysis—so samples must be collected first.

Phenolphthalein is considered to be the most sensitive (1:10,000) and is recommended for testing small droplets or smears. This reagent produces a pink stain, which is presumptive of the presence of human blood.

Leucomalachite can be used on larger concentrations of blood and it produces a green/blue stain, but it is not as sensitive as phenolphthalein.

Use the contact method of testing with these two reagents, transferring blood from the suspect stain to a cotton swatch saturated with distilled water for testing, rather than applying the reagent directly to the stain.

Presumptive Blood Identification Procedure

Phenolphthalein and Leucomalachite application principles are identical. These two reagents are supplied in disposable chemical applicators (DISCHAPS) or in glass ampoules.

Photo Ampoules:

 

If the possibility exists that blood stains have been cleaned up, then examination of the area should be undertaken using reagents such as Luminol, Blue Star, Lumiscene, etc. These reagents produce a blue luminescence. Luminol may only be seen in total darkness while Blue Star and Lumiscene may be viewed under low light conditions

Searching For Latent Blood Prints

Latent foot prints occur when someone steps in blood as they navigate around the crime scene. With each step blood is deposited onto the surface. Many times these visible impressions show very little visible detail because of saturation, but later diluted steps, that are not visible to the eye, can reveal these details with astute processing. It isn’t until several steps are taken that these impressions become visible.

Several different chemical formulas are available to restore the latent foot print to visibility.

The same thing occurs when the person at the crime scene has blood on his fingertips and he leaves latent blood fingerprints as well.

Below are listed four different reagents that have been successful in producing visible blood prints in numerous crime scenes.

Leuco Crystal Violet is one of the most sensitive reagents and one of the most popular for use at crime scenes.  Individual components are packaged in separate containers since the mixture becomes unstable after a short time. This reagent does not react to the normal finger constituents found in latent fingerprints like eccrine or sebaceous deposits. Rather, this reagent has an affinity for heme-based materials, such as hemoglobin in the blood. Developed latent blood prints are violet in color. This reagent may be sprayed on the surface or tray-development may be employed. This reagent works best on non-porous surfaces.

Coomassie Blue is another reagent that will enhance latent fingerprints and foot prints contaminated with blood on porous and non-porous surfaces. The working solution is sensitive to the proteins found in blood. If weak prints are observed after applying the reagent, the procedure may be repeated for maximum contrast. Latent blood prints will be blue in color.

 

Hungarian Red is a powdered dye but is available in premixed form. Hungarian Red is the outcome of an effort by police forces in Hungary and Holland. Researchers sought a formula that would be highly sensitive to blood residue, and subsequent testing here in the U.S. indicates that this reagent may be more sensitive than other methods such as Amido Black. Hungarian Red also has fluorescent properties and may be viewed with an alternate light source operating in the range of 520 to 560 nanometers.and is viewed with a red filter.

 

Amido Black is a biological dye that stains the protein present in blood and some other body fluids, producing a dark blue-black image. It is extremely useful in developing latent fingerprints contaminated with blood, but cannot be used on dark surfaces, as it will be hard to visualize the stain. Amido Black can be used on almost any surface, porous and non-porous; however, some porous surfaces will completely stain, hiding any detail of the prints. It can be used on the skin of corpses, but it should not be used on live skin. Be certain to check with the medical examiner/coroner prior to applying reagent to corpses.

 

Part 2. of this series will offer specific formulations for the reagents listed above. If you are interested in gaining more information on crime scene investigation, you are invited to download a free copy of the training manual, “The Evidence Collection Mission.” You may retrieve your copy by Clicking HERE. Evidence Collection Manual

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