Chemical Processing

Leucocrystal Violet

Reacts with the iron in hemoglobin in blood, turning the stain a purple/violet color

Used to search for bloodstains, develop latent prints/patterns, and enhance detail

LCV

Can be used after Luminol when trying to distinguish bloodstains but must be used prior to Luminol when pattern evidence is of interest

Least destructive and can be used on most surfaces

Applied prior to Amido Black

Rinse with water/methanol optional but not required

Amido Black

Not blood specific but a protein stain

Stains blood a blue-black color

Amido Black

Used to search for blood and enhance detail in prints/patterns

May interfere with other forensic examinations (handwriting, indented impressions, body fluids, fibers, etc)

Will not detect normal constituents of latent fingerprints

Requires rinse with water or methanol

Luminol

Exhibits chemiluminescence with a blue glow

Reacts with iron in hemoglobin

Luminol

Used to locate and visualize diluted blood and areas of cleanup

Can also react with other chemicals and food

Used last in the chemical sequence if pattern evidence is of interest

Can potentially inhibit DNA analysis. Swab visible stains prior to application

LCV

**Use prior to Amido Black***

Take general photos of area where chemical processing will be completed

Process all suitable surfaces using clean techniques with BLACK POWDER prior to application of chemicals, as necessary

All friction ridge detail visible before chemical processing shall be comparatively photographed

LCV

Lightly spray LCV to print/pattern/area. Rinse as needed. Allow to dry.

Comparatively photograph any enhanced ridge/pattern detail. Label scale LCV.

Search other areas outside of obvious stain as well. Better pattern evidence may be present in these areas.

Photo credit: BVDA

Amido Black

Take general photos of area where chemical processing will be completed

Process all suitable surfaces using clean techniques with BLACK POWDER prior to application of chemicals, as necessary

All friction ridge detail visible before chemical processing shall be comparatively photographed

Lightly spray Amido Black to print/pattern/area of interest. Can be sprayed over LCV.

Photo credit: Science Direct

Rinse as needed with water or methanol

Comparatively photograph any enhanced ridge/pattern detail. Label scale Amido Black.

Luminol

Take general photos of area where chemical processing will be completed

Set up camera equipment to be ready to use. Darken environment as much as possible.

Luminol

Apply solution in a sweeping motion starting at farthest end of area of interest. AVOID saturating area.

Photograph any areas with chemiluminescent blue glow as quickly as possible.

EPU Tips

Any powder applied to the bloody pattern/print will not create an impermeable layer for the reagent. The powder residue will wash off when the reagent is applied.

Try applying the blood reagent twice; once to remove the powder and then another to make sure the surface is coated

Tips from EPU

Powders are typically used on the not-so bloody areas, not the super blood-dense areas. Think of the areas surrounding the bloody impression that could potentially have latent prints.

If possible, collect the item to be processed in the lab in a more controlled environment. Or see if the scene could be held longer to ensure proper processing and collection techniques are completed.

Photo credit: Inked Pixels/Shutterstock