Fingermarks

Question 1

Main objective of Fingermark Enhancement

Answer 1

+ obtain the best optical contrast possible between the FINGERMARK RIDGE PATTERN & the UNDERLYING DEPOSITION SURFACE without destroying any available ridge detail

Question 2

Plastic Fingermarks

Answer 2

+ VISIBLE marks in SOFT SURFACES (e.g. Putty, Wax)

Question 3

Patent Fingermarks

Answer 3

+ VISIBLE MARKS

- made in blood or paint for example

Question 4

Latent Fingermarks

Answer 4

+ INVISIBLE to the NAKED EYE unless enhanced - commonly made in Sweat

Question 5

Visualisation & Enhancement Reagents for examination of Latent Fingermarks

Answer 5

POWDERS
- Aluminium Flake
- Granular Powders
- Magnetic Powders
ALL USED ON NON-POROUS SURFACES

Question 6

Aluminium Powders

Answer 6

\+ Flake powder
\+ More sensitive than other powder types
\+ Used on SMOOTH, NON-TACKY surfaces
\+ Unsuitable for ROUGH, TACKY or WET surfaces
\+ Applied using a GLASS FIBRE brush

Question 7

Granular Powders

Answer 7

+ Commercially available
+ Most SENSITIVE on SMOOTH surfaces
+ May not LIFT as well as Magnetic Flake powders
+ Black/White/Fluorescent varieties available
+ Applied using an ANIMAL HAIR brush

Question 8

Magnetic Powders

Answer 8

+ Application CONVENIENT but LESS EFFECTIVE than aluminium
+ More effective on GRAINED SURFACES
+ based on Metal/Metal Oxides which r FERROMAGNETIC
+ Applied using MAGNETIC brush

Question 9

Powders Adv & Dis

Answer 9

Adv

Question 10

Small Particle Reagent (SPR)

Answer 10

\+ Molybdenum Disulphide in suspension
\+ Adheres to FATTY CONSTITUENTS
\+ Grey Deposit
\+ DISH application preferred to SPRAY
\+ Suitable for NON-POROUS surfaces (polythene, waxed surfaces & gloss painted articles)
\+ NOT SUITABLE for POROUS surfaces

Question 11

SPR Adv & Dis

Answer 11

Adv

Question 12

Vacuum Metal Deposition

Answer 12

+ Evaporation of METALS followed by Deposition in thin films
+ Thin layers of ZINC & GOLD
+ Disturbances in PHYSICAL & CHEMICAL layers on surface cause UNEVEN DEPOSITION of Zinc
+ Used on SMOOTH NON-POROUS surfaces
- can be Effective on GLASS, PLASTIC MOULDINGS, SMOOTH LEATHER
+ Not SUITABLE on POROUS surfaces
“+ GOLD covers complete surface & PENETRATES FINGERPRINT deposit
+ ZINC binds to gold on surface (not where it’s diffused into print)

Question 13

VMD Adv & Dis

Answer 13

Adv

• Extremely SENSITIVE
• Effectively develops OLDER FINGERMARKS
• develops fingermarks that have been EXPOSED to WATER

Dis

• reverse deposition issue if FINGERMARK DRIED OUT
• requires EXPERIENCED OPERATOR
• High Initial COST

Question 14

Cyanoacrylate (Superglue Fuming)

Answer 14

+ Superglue vapour POLYMERISES on LATENT PRINTS leaving a White Deposit
+ polymerisation occurs due to CATALYSATION of water/other constituents
+ Atm press, RT & 80% humidity required for optimisation
+ Fluorescent dyes can be used after
+ Used on NON-POROUS surfaces

Question 15

Cyanoacrylate Adv & Dis

Answer 15

Adv

• Easy to use
• Increases RESISTANCE of fingerprint ridges to DAMAGE
• Useful on ROUGH surfaces (vinyl, rubber)

Dis

• can INTERFERE with further examination
• H&S - operator can’t be exposed to vapour/liquid monomer
• Must be used in chamber fitted with extraction system
• developed fingerprints can be DIFFICULT to SEE & RECORD even on dark surfaces
• use of fluorescent dye essential to maximise num of prints
• not suitable for WET ARTICLES

Question 16

Ninhydrin

Answer 16

+ Reacts with AMINO ACIDS
+ Provides final PURPLE coloured product known as RUHEMANNS PURPLE
+ Produces IMMEDIATELY VISIBLE PRINTS
+ Used on Paper, Cardboard & POROUS Surfaces (wood)
+ use of HEAT speeds process & produces more marks
+ some development continue so prints may appear some time later

Question 17

Ninhydrin Adv & Dis

Answer 17

Adv

• Simple to use & very EFFECTIVE
• will detect fingerprints many YEARS OLD
• will develop fingerprints on Porous surfaces soaked with PETROL/PARAFFIN
• RAPID - majority of prints will develop during heat treatment if conditions optimum
• Develops fingermarks in BLOOD on most surfaces

Dis

• won’t develop fingermarks on articles which have been EXPOSED TO WATER
• small num of prints may take several weeks to develop fully
• fingermarks may develop if handled after treatment