Chapter 10: Basic Skills for Scene Processing: Fingerprint Evidence

Fingerprint guide for adhesive tape: Dry Surface

- Adhesive side of Tape - If possible submit to the crime Lab - On Scene Examination: Straighten the tape. If wadded consider freezing and or solvents then straighten. Then Use: 1. Crystal Violet, alcohol/ water technique 2. Sticky side powders - Match any treatment of the backing side of tape (e.g fabric/plastic cellophane, paper) with the most appropriate process given its surface.

Fingerprint guide for adhesive tape: Wet Surface

- Allow to dry - and use any of the techniques in the dry surface

Latent prints

- Are effectively invisible. - They occur as a result of oils and secretions from the friction ridge surfaces being deposited through contact. - Latent prints generally require some sort of development to visualize, but can occasionally be visualized with oblique lighting.

Plastic prints

- Are true dimensional impressions. - They result when a friction ridge surface is impressed into a pliable material such as window putty.

Patent prints

- Are visible prints. - They result from friction ridge surfaces that were contaminated in some fashion (e.g., blood, paint) coming into contact with another surface.

Fingerprint guide for bloody fingerprints: Wet Surface

- Dry surface then apply techniques from dry surface

Permanence

- Fingerprints develop about the third month of gestation and remain consistent throughout the life of an individual barring permanent damage to the papillary ridges or total decomposition.

Fingerprint guide for non-porous smooth surfaces: Dry Surface

- If Possible, seize and submit for crime lab exam - On scene examination 1. Cyanoacrylate Fuming 2. Dye stains or powder 3. Small-particle reagent - Silver Nitrate may work on some plastics - Iodine Fuming may be effective on fresh prints other than those located on metal

Fingerprint guide for non-porous rough surfaces: Dry Surface

- If possible seize and submit to the crime lab - On Scene Examination 1. Cyanoacrylate Fuming 2. Powders (Consider Fluorescent for Contrast) - After powdering use silicone based casting material or textured surface lifting tape to remove the print

Fingerprint guide for bloody fingerprints: Dry Surface

- If possible submit to the crime lab - On Scene Examination: Visible Bloody Contaminated Prints 1. Photograph and lift 2. Amido-black 3. Leuco- crystal violet - Latent Bloody Prints 1. Amido-black 2. Leuco-Crystal Violet 3. Fluorescien (alcohol-based not aqueous) - Never use luminol or aqueous based fluorescien in an attempt to develop latent prints

Fingerprint guide for porous surfaces: Dry Surface: Untreated Wood

- In the order presented 1. Ninhydrin 2. Powder/ Brush

Porous Surfaces: Iodine Processing

- It can be applied with airbrush systems which allows for large areas such as walls (paint and paper) to be processed quickly and effectively. - prints are fugitive, meaning they fade quickly and must be photographed as they are developed. - produces dark brownish color prints. - very corrosive and produces harmful vapors and requires knowledge and training to use. - It works extremely well on very fresh latent prints.

Porous Surfaces: Indanedion

- It works much better on hard to process surfaces such as currency and produces greater detail in the florescence print. - requires a cyan light source (in the 475-nm range) paired with an orange barrier filter.

Non-porous rough surfaces

- Items such as vinyl, treated leather, or textured surfaces represent a problem for both developing and lifting latent fingerprints. - Once again, the standard seize and submit advice should be followed whenever possible. - include cyanoacrylate fuming followed by dye stains or powder and brush. - rough or irregular surfaces present a significant difficulty. Using standard lifters (e.g., hinge and tape lifts), the latent is often recovered in a fragmented condition or with too much background detail from the surface, effectively making it impossible to see the detail of the latent. - Rough-surface lifting tapes are available for this condition as well as a variety of silicone compounds. - Both reduce this effect and increase the probability of recovering a functional latent print. - Silicone lifting material is also an effective response when presented with a surface that is not firm enough to apply pressure to a standard lifter or lifting tape, and in cases where the shape of t

Individual

- No two fingerprints have ever been found to be exactly the same; not from direct comparison, classification systems, computer databases, not even from identical twins. - Fingerprints are unique to the individual.

Fingerprint guide for porous surfaces: Dry Surface: Paper

- On Scene Examination 1. DFO 2. Ninhydrin 3. Silver Nitrate

Fingerprint guide for non-porous smooth surfaces: Wet Surface

- Seize and Dry - Followed by any of the dry surfaces process - Small particle reagent

Fingerprint guide for non-porous rough surfaces: Wet Surfaces

- Seize and dry - Followed by the powder and brush technique

Fingerprint guide for porous surfaces: Wet Surface

- Seize and dry - followed by physical developer

Fingerprint guide for human skin: Wet Surface

- Use Machine Paper Technique which is not negatively impacted by moisture

Nonporous smooth surfaces: Collection

- any surface that does not absorb moisture. - Examples include metals, glass, plastics, ceramics, guns, knives, bottles, baggies, or finished wood products. - Stabilization of the latent prints and transport to the lab is the best approach for collection of this type of evidence. - This stabilization is accomplished through cyanoacrylate fuming (superglue fuming). - This can be accomplished on scene with a portable fuming chamber or the evidence can be fumed at the first available opportunity at the office or crime laboratory. - latent prints are stabilized on a non-porous surface, although standard brush and powder techniques are effective for recovering latent prints; dye stains such as Rhodamine 6G, Ardox and 7-(p-Methoxybenzlamino)-4-notrobenz-2-oxa-1,3-diazile (RAM) may be a more effective approach. - Fluorescent powders in use with an ALS are effective when dealing with difficult surfaces that do not provide sufficient background contrast. - Small-particle reagent (SPR) is

Major case impressions involve

- both standard ten print as well as all friction ridge surfaces (palms, sides and full lengths of each finger).

classification with the Henry system

- dealt with more than just the basic fingerprint pattern, it also involves ridge counts in the loop pattern, direction of ridge flow in the whorl pattern, ridge disruption in the arch pattern, whether a ridge flows in or out of patterns, and whether they flow toward or away from the thumbs.

Porous Surfaces: ninhydrin (2,2-dihydroxyindane-1,3-dione)

- develops the alpha-amino acids in the latent print. - produces a purple color print - prints are also fugitive and the process often depletes all of the alpha-amino acids in the latent which the ninhydrin reacts to. - scene processing will hinder the ability of the crime lab to develop or re-develop a print, thus it is accomplished only when the item/surface cannot be collected and sent to a lab - are visualized with a variety of laser and ALS light/filter combinations. These include: a cyan light (490-520-nm) paired with an orange filter, a green-light (520-550-nm) light paired with either an orange or red filter or an amber light 588-595-nm paired with a red filter.

Porous Surfaces: Collection

- includes any item that can absorb moisture. - Examples include paper, untreated woods, cardboard, currency, checks, and various forms of packaging material. - to simply wrap it in paper, place it in an envelope or cardboard box and transport it to the crime laboratory where proper chemical treatments will produce the best results. - the majority of porous items encountered in crime scenes lend themselves to collection and transport. - Field processing this type of evidence routinely results in damage and loss of evidence. - Once prints on this type of evidence are developed they must be captured immediately as they are very susceptible to destruction and fading. - Never use powders on paper, as it hampers additional processing techniques. - In instances where collection is not possible, chemicals which work in developing prints on porous evidence include iodine, ninhydrin, 1,8 diazfluoren (DFO), and physical developer. - All of these processes are best accomplished in a laborato

The science of fingerprints is based on two fundamental principles relating to friction ridge skin

- individuality and permanence

fingerprint classification

- involves the filing and retrieval of fingerprint cards, and fingerprint identification involves the comparison of known prints (record prints) with unknown prints found at crimes scenes for express purpose of identification. - the application applied to fingerprint pattern interpretation, ridge counting, and ridge tracing.

Identification

- the method of analyzing, comparing, and evaluating a latent fingerprint to record or known fingerprints for the purpose of determining if there is a true match or "identification". - Upon close examination of record fingerprints, the details in the friction ridge surfaces are unique to every finger. - These details are comprised on three basic types: dots, ending ridges, and bifurcations.

Ten print classification

- the process used to define an alpha numeric formula to a set of record fingerprints of an individual for the purpose of filing and retrieval.

Porous Surfaces: Physical developer (PD)

- used on a porous surface only after all of the previous mentioned processes are completed, as it will wash away all constitutes of fingerprint residue to which the previous processes react to. - That is why PD is used on previously immersed or water soaked porous evidence. - PD reacts primarily with the salts, fats, and waxes in a latent print. - PD requires the mixing of several solutions, silver nitrate, with prewashes, and rinses and is not generally recommended for field use.

Friction Ridge Skin

- which is found on the palmar side of the hands and fingers and the plantar side of the feet. - aids in grip and locomotion

Porous Surfaces: 1,8 diazafluoren (DFO)

- works much like ninhydrin but produces florescent orange color print - best visualized using a cyan light (490-520 nm) paired with an orange barrier filter.

Fingerprint guide for human skin: Dry Surface: Dead on scene examination

1. Adding Machine Paper Technique 2. Cyanoacrylate Fuming 3. Magnetic Power 4. Iodine Fuming

Fingerprint guide for human skin: Dry Surface: Alive On Scene Examination

1. Adding Machine Paper Technique 2. Smooth Plate Technique

The standard methodology of fingerprint comparison

ACE-V method of comparison

Special conditions

Anomalies such as human skin, adhesive tapes, and blood prints

Three basic fingerprint patterns

Arch, Loop, and Whorl.

AFIS

Automated Fingerprint Identification System - utilizes an algorithm that is based on spatial orientations of ridges, as the system does not specifically see loops, whorls and arches

Porous surfaces

Paper, cardboard, untreated wood

Nonporous smooth surfaces

Varnished and painted surfaces, plastic surfaces, glass

Nonporous rough surfaces

Vinyl, textured countertops, and other textured surfaces

fingerprint dot

a ridge that is no longer than it is wide

ACE-V

analysis, comparison, evaluation, verification - includes both qualitative and quantitative analysis produce conclusions, which are reproducible. - The comparison and evaluation of friction ridge skin is based on the examination of ridge flow, ridge paths, location, direction, spatial relationships, ridge structure, edgeoscopy (the microscopic edge detail of a ridge) and poroscopy (the study of the pores in a print).

bifurcation

where a fingerprint ridge diverges, or separates as in a fork in the road.

ending ridge

where a ridge comes to an abrupt ending