Latent Prints Wk2

FRSC 350 - Lisa Gilbert

What are the four types of processing techniques?

1. Non-porous

2. Porous

3. Wet

4. Blood

What is a non-porous surface?

A surface that doesn’t absorb water.

What are the steps/techniques used for non-porous surfaces?

• Visual (laser/ultraviolet light)

• Superglue fuming

• Powdering

• Chemical dyes/stains

Why is the processing order of non-porous surface not changable?

The least destructive methods must be used first.

How does photography integrate in the sequence for non-porous surfaces?

Even through it is not necesarily a step, photogprahs should be taken consistantly in-between every step.

What is the most imporant step in non-porous surface processing?

The visual step, ensure photographs are taken consistently.

What is the first step in processing of non-porous surfaces?

Laser/UV analysis.

How does laser/UV light work for fingerprint analysis?

Excites natural residue to glow under hight contrast.

What is the step after laser/UV light in processing prints of non-porous surfaces?

Superglue fuming.

What is the sceintific name for superglue?

Cyanoacrylate ester.

What is the process for superglue fuming?

My placing evidence in a large chamber and heating a liquid superglue to create vapors that will chemically react to moisture and chemical residues hidden in the print.

Why is superglue a good step to do before other testing?

The superglue will set the print permanently in place, creates a durable shell over the print.

What are advantages of the superglue shell on non-porous surfaces?

It absorbs the dyes, staints, makes clearer visuals for photographs and produce good lifts without removing the print form the surface.

What is the next step after superglue fuming in processing prints of non-porous surfaces?

Powdering.

What is the powdering step in processing prints of non-porous surfaces?

Brushing on delicate fine powders on the evidence to attach to the print for lifting.

What are the different kinds of powders that can be used for print powdering on non-porous surfaces?

• Black

• Magentic

• Colored

When are white and silver powders used? What are their disadavantages?

On darker surfaces however they are harder and not recomended to use since they can stick to the surface as well making it harder to see the print.

What is a powdering brush like?

A long bristle fiberglass brush.

Why is fiberglass the material of the powdering brush bristles?

They are extremly fine and tend to split, makes even finer bristles.

What is magnetic powder like?

A fine magnetic powder that uses a magnetic want to pick it up and brush it over the print.

Why is magnetic powder technically the softest application?

Magnetic wand does not even touch the surface of the evidence.

What is the best kind of powder in experience?

Classic black powder.

What is the step in powdering processing after dusting the powder on the surface?

Unofficially, taking a photograph of it, but officially lifting the print.

What is lifting a print?

A way to preserve the latent print and allow for better analysis.

What are the different ways to life a print?

1. Lifting tape

2. Hinge lifters

3. Rubber lifters

4. Microsil

What should be done with a lifted print?

Place it on a card/paper that contrasts the color of the powder used.

What is the step after powdering prints in non-porous suefaces?

Dyes and stains.

What is a kind of dye/stain used first in non-porous surfaces?

Rhodamine.

What is rhodamine?

Dyes that glow an orangey red liquid dye when mixed with either methanol or water.

What solution percentage is rhodamine solution created in?

0.01% to 0.1%.

How is rhodamine dye used?

Is sprayed onto the evidence for complete coverage and left to dry in the fume hood.

How is rhodamine stained latent prints viewed?

Under a diode laser light at a wavelength of 514.5nm with laser goggles for protection.

What must be used in order to capture images of rhodamine prints under laser?

A sort of orange filter.

What does rhodamine look like under laser?

A fluorecent yellow glowing print.

What is the next dye/stain used after rhodamine on non-porous surfaces?

An Ardox stain.

What is an Ardox stain?

A liquid stain whose solution is made from either methanol or water.

How is an Ardox stain used?

The liquid is sprated onto the item and allowed to dry under the fume hood.

How are Ardox stained latent prints viewed?

Under ultraviolet lights at 400nm range with UV protection goggles.

What do Ardox stained latent prints look like under ultraviolet light?

Fluorecent.

How are dye/stains prints preserved?

Through photography.

What must be used in order to capture images of Ardox prints under laser?

A UV (2E) filter.

What is used in non-porous evidence processing of something that has been wet?

Small Reagent Processing, a solution that adheres to greasy impressions left on wet items.

Which stain is better for latent print on non-porous surfaces?

Both, evidence reacts differently to both, rhodamine might work better for some, and Ardox for others.

What is a porous item?

An item whose surface can absorb water.

In porous surfaces, what protects the print?

The material itself, through absorbance there is no way for the print to get rubbed off.

What are the steps for porous print processing?

1. Visual (laser/UV)

2. Iodine (outdated)

3. Dyes and stains

4. Physical developer

What are the 4 types of dyes and stains in porous fingerprint development?

1. DFO

2. 1, 2-incandedione

3. Ninhydrin

4. Zinc chloride (laser)

Are the porous print processing steps flexible? Why (not)?

No, their order must not be changed because the are ordered by least to most destructive.

What is an unofficial step in every porous print delvelopment?

Photography used after every visible print step.

What should one do if the porous evidence is given to them wet?

Skip all steps and place it straight in the physical developer.

What is the visual step like in porous surfaces?

Laser causes fingerprint residue to glow, an example is vitamin B12 that will glow under 570nm laser (same in non-porous).

What do the chemicals used in processes react with that produce visible prints?

The amino acids from the perpetrator’s hands.

What does iodine fuming require the print to contain in order to bond?

Oils/fatty materials.

What is the iodine fuming method like? Why is it not used anymore?

Iodine crystals are placed into a ziplock bag with the evidence and shaken, it is not recommended for a print 10+ days old due to fat breakdowns, however this is not used anymore becasue it is cancer causing.

Are iodine fumed prints permanent?

No, one reason pictures are so important.

What do iodine fumed prints look like?

Brown in color.

What does DFO processing like?

Produces faint pink or red impressions.

How is DFO viewed?

Under a 530nm laser.

What is used to accelerate DFO print results?

Heat, about 100°C.

What can be used to enhance the porous print from DFO?

Ninhydrin produces the best enhancement.

What do 1,2-Indanedione prints look like?

Faint pink prints under white light.

What is used to view 1,2-Indanedione prints?

A laser at 520nm.

What can be applied to speed up the reaction of 1,2-Indanedione?

Heat and humidity.

What can be used to enhance 1,2-Indanedione prints?

Zinc chloride.

What is the best porous print impression technique called?

Ninhydrin.

What is Ruhemann’s complex?

The deep purple tones that form from using the ninhydrin method of print processing for porous surfaces.

What solution is ninhydrin used in?

A .5-1.0% solution mixed with vertrel.

What used to be mixed with ninhydrin to make its solution?

Started with freon, then petroleum, then ether, and now vertrel.

What are the methods of application for ninhydrin?

• Aerosol (spray)

• Immersion

• Paitning

What must be used for the ninhydrin reaction to form?

Heat (70°C) and humidity (70 RH).

How is ninhydrin used?

The porous material is covered in the solution and placed to dry in a fume hood before waiting 1-2 hours for print to develop in chamber of heat and humidity.

What must be used in order to photograph ninhydrin prints for analysis?

A green filter is purple ridge detail shows.

What does zinc chloride work best on?

Wood.

What color does zinc chloride turn into? Why?

Orange, since its used after ninhydrin (usually), metals bonding to Ruhemann’s complex turn orange.

What is zinc chloride in terms of effictivity?

Technically just a color change, but the orange can fluoresce at 488nm.

How does a physical developer work?

The solution used reacts with lipid materials through a Red/Ox solution that creates a silver coating of lipid based ridge detail.

What does evidence that has been through a physical developer look like?

Almost powdered look, grey, soft print results.

What is the most nitpicky part of using a physical developer?

This technique is extremley sensitive and requieres no metal at all on the paper, wooden or rubber utensils should be used.

What is Oil Red-O (ORO) used for?

Used to enhance fingerprints on porous surfaces by attachning to lipids of fatty substances (oils of any kind).

When is ORO useful?

On porous surfaces that have been wet.

Is ORO processing common?

No, even though it is less complex than the physical developer, it got aged out.

What is the process of ORO processing?

1. Processed direclty in ORO solution (5 to 10 minutes)

2. Placed in buffer solution for 5 minutes

3. Rinsed in water

4. Dried

5. Photographed

What does an ORO print look like?

A clear, red-toned impression.

What is the main concern when it comes to bloody evidence processing?

Which department needs it more/first? Whether the biological DNA department must use it first for a DNA profile generation.

Why does DNA processing of bloody information surpass importance of latent print processing?

DNA cannot be analyzed with a photograph and scale like latent prints can.

What is a semi-porus item?

Item that can be a little porous, like notebook cover.

What is bloody evidence on a porous item usually analyzed with first? Why?

Ninhydrin because it attaches to the proteins in blood.

What is bloody evidence on a non-porous item usually analyzed with first? Why?

Amido black, can be done post-superglue.

What is amido black processing?

A chemical dye solution that reaacts with proteins in blood.

What is amido black made up of?

Glacical acetic acid and methanol.

What are the proteins in blood that processing techniques adhere to?

Plasma/serum portions.

What other stain can be used in non-porous bloody prints for processing? Why would this method be chosen?

Crowle’s stain, chosen when methanol would be too harsh on the evidence and cause an adverse reaction since it is water-based.

Before processing of bloody evidence, what must be done on the print?

It must be denatured to fix it on the item and prevent it from dissolving in solution, most stains however include one.

How and what must bloody evidence be stored in?

Dry in a paper bag to prevent moisture build-up that leads to molding.

What are techniques used on tape to get a latent print?

Sticky/adhesive side powder.

What is the process of Sticky-Side powder?

A 1:1:1 mixture is prepared of powder, photo-flo (film developing liquid), and water, which was then brushed on the sticky side of tape and left for 10 seconds before being rinsed off and photographed.

What is a substitute for actual sticky side powder? Why?

Ordinary powders can be used in replacement since the process and mixture is what creates the developing.

What is the acronym for comparison/identification?

ACE-V.

What does ACE-V stand for?

• A: Analysis

• C: Comparison

• E: Evaluation

• V: Verification

What are the first level of detail of ACE-V?

Ridge flow (patterns: loop, whorl, arch).